Realistic performance goals for light build-up of 1UZFE

The 1UZFE EGR Delete Kit is available for sale here.
OK notice where you have dropped 111 rwkw from your number?

turning 8000rpm could make 450 flywheel hp (335 rwkw for you aussies)

He made typo, he meant 335 flywheel kW, or about 215rwkW

Keep looking at this thread.

I have intake (sort off), manual trans, aftermarket ecu, and custom 4-2-1 extractors.

I am getting it dyno tuned tomoz (partly tuned anyway, we are very pressed for time), and I'm hoping for 160-170 rwkw (or 215-230rwhp)

But who knows, it may be more, it may be less.

I'm not even sure if the car is running perfectly

Will keep this updated.
 
Again, here is my quote "A really good exhaust could gain 40rwhp"... please note the parts about "really good" and "could"...

Sure. But you will not gain near 40rwhp from the exhaust. If you changed all of it, with really good headers and high flow cats, then a catback might net 20rwhp. As I said.

Automatics dyno lower due to the torque converter slipping. The lockup function does not engage while acclerating.

For the record, the Viper is detuned, and underrated. The old 450 hp version made 425 rwhp even in Motor Trend through the power sucking T56. But that engine is no comprarison to the 1UZFE, in my opinion.
 
Peewee said:
He made typo, he meant 335 flywheel kW, or about 215rwkW.
Well even so, I don't see how 335fw is 215rw. Unless your flywheel rating is done by Holden or Ford of Australia.
 
Nick M said:
Sure. But you will not gain near 40rwhp from the exhaust. If you changed all of it, with really good headers and high flow cats, then a catback might net 20rwhp. As I said.
Exactly. The title of this thread is "realistic".
 
Miles B said:
OK notice where you have dropped 111 rwkw from your number? OK..

Secondly, there was a Soarer converted to 5 speed manual here and dynoed, and it LOST a couple of horses. What is so "power taxing" about the A341? Yes it is soft, but that is just the shift logic involved. The planetary gear set in it is about the same inertial load as a pair of shafts of gears in a manual box, and when the converter locks up, that's locked up like a manual's clutch.

The Viper must be doing something right - yes it is a 2 valve engine, but stock it dynos about 415rwhp. Halve that and you get 207rwhp. Which is more than my space age 1st gen V8 Soarer ever did AND the Viper does it with a lower compression ratio. Tell me how they pull that off.

The US Honda website says the S2000 is actually a 2.2 litre engine with 11.1:1 compression ratio and an 8000rpm redline, with its power peak at 7800rpm. It also shows the S2000 as having an UNDER square engine. Previous years I believe were almost square or very slightly over, and actually peaked at 8300rpm with a 9000 redline.

The 8L Viper is over square, has a fuel cut redline of 6200rpm. The redline on my car is 6250. Many have raised the redline on the Viper by 500 or 750.

The title of this thread is actually "light build-up of 1UZFE". That does not involve dropping in a 4.3. Yes, by changing engines you might get near 300rwhp.

I had a quick read of the threads you posted. We have:
262 with exhaust, intake, ECU
255 with same
249 K&N intake
249 K&N filter
230 stock / with exhaust

From your post, I was expecting to see "270 with no exhaust". What I see is a car with 262 with everything except (maybe) extractors. Which may add another 15 or 20 if they are REALLY good. I have seen a lot of headers and extractors put on cars. The best results I have seen was a set that cost in excess of 2500 US dollars, put on a Viper, and yielded mid 40s hp with exhaust. These were tuned length, lots of work done, real science. And they yielded just over 10%.

I hear a lot of people saying "get a really well designed exhaust and you'll pick up 50hp", but I don't see anyone doing it. Please prove me wrong. The fact is most people pick up 15hp with the first one they put on. For some that is the exhaust, for others it is the headers. Then people say "sweet, they add 15 each". Then 15 becomes 20, and 20 becomes "25 if you use a lot of science". The results are usually what Peter Scott shows. 15 for the first, and half that for the second.

Miles, I am sorry but I really do not believe you are reading my posts carefully. I said "A full out effort on this base package, turning 8000rpm could make 450 flywheel hp (335 rwkw for you aussies)" this was NOT referencing this posts goals but rather the potential for this engine... actually... I believe there is more POTENTIAL power than 450hp/335kw but lets not argue that point here. Then I said "The title of this thread is Realistic buildup. Take the 270rwhp above and add a realistic 30rwhp with a well sorted exhaust and you get the target 300rwhp or 224rwkw". The 224rwkw from one post is NOT a reduction of 111rwkw from another. If you see above I said 450 flywheel horsepower and then threw in 335rwkw by mistake... that should have read 335 flywheel kilowatts as 450hp = 335kw.

Regarding the example you post above about a 5 speed conversion on a Soarer... sorry... but there is more to drivetrain loss than the tranny AND multiple documented examples show that most automatics consume more power during acceleration than most manual trannys. The discussion of drivetrain loss is complex and not suited to add to this thread BUT... I stand by my statement that the stock 1998+ LS/GS/SC drivetrain looses around 22% and that a lightweight and solidly attached drivetrain (such as a 5.0 Ford Mustang tranny and axle assembly, common stuff for kit car use) is docummented in the 15% loss range. Take the 1UZFE or 3UZFE out of the Lexus and install it in the kit car and you have more power at the wheels with no other changes.

I apologize if I left the impression that I do not like Vipers (or Corvettes) or other single cam OHV engines. The Z06 Corvette makes 405hp with 5.65 liters. I like that engine a lot. That said, there is flat more maximum power potential per liter in the 32v DOHC Toyota/Lexus engines. Don't you agree? My comments were based on being accused of incompetence regarding my prediction of 450hp potential from these engines. I stand by that. Regarding how the Viper makes as much power as it does compared to your Soarer engine? Valve timing and lift combined with enough flow capacity for the rev range. The Vipers engine is much closer to power optimized than your Soarer engine which was designed for smooth adequate power.

Yes the current S2000 is 2.2 liters/240hp but it was originally 2.0 liters/240hp. The current version even meets the tough California low emission vehicle (LEV) standards. The reason I used it as an example was not to suggest copying it... rather as yet another example of how much power can be made WITH emissions equipment on pump gas. This is to support my suggestion that 450hp is obtainable with the 1UZFE and I did not state it would be emission legal or even run on pump gas... just very very possible.

Your statement... "The title of this thread is actually "light build-up of 1UZFE". That does not involve dropping in a 4.3. Yes, by changing engines you might get near 300rwhp"... is an assumption that this would be an engine change... it is not since Kreb had not yet installed an engine in his kit car... "I've just started looking at junkyards for 1UFZEs and it's amazing how cheap and available they are" ...we are not talking about changing engines at all. So, it made more sense to source the higher capacity/newer/better technology engine from the start and it appears he agrees with me. I think the continued criticisms of my statements is not helping him... in fact probably needlessly worrying him... the truth is... as you now aparently agree... that 300rwhp is doable with minor mods on a 3UZFE in a kit car application. That was his goal and I gave him a very straight forward realistic plan to accomplish that. This plan is probably much cheaper than obtaining the same power if starting with the earlier 1UZFE engine.

Your statement... "What I see is a car with 262 with everything except (maybe) extractors"... is inaccurate. The mufflers on a GS430 do nothing for power, that is not where the exhaust is restrictive. That car (first link I give) changed mufflers and dyno'd with no power change (re-read the above link for that info). He than added the SRT intake which comes with the so called "race ECU" which is nothing more than a re-calibration of the A/F ratio to compensate for the fact that the stock MAF element is being used in a larger tube and therefore MUST be recalibrated to prevent damaging super lean running. This car is STOCK exept for the intake mod. The stock exhaust Y pipe is dual 50mm pipes (1.96") feeding a single center 60mm pipe (2.36") hardly a maximized exhaust. If you review the manifold pictures I posted in the exhaust thread you will see a major area of possible improvement with tuned headers. As far as price on headers go... I am not impressed by expensive parts... only parts that function properly. Excellent headers can be custom fabricated for well under $2000USD. Your statement "I was expecting to see "270 with no exhaust" is actually less than what that engine would make in the intended kit car (using my assumption of 15% loss vs 22% loss) and should make apx 285rwhp. Now, that example is one of the more powerful dynos I have seen for a 3UZFE with the SRT intake. 250-255rwhp is more like it or 270-278rwhp (installed in the kit car) is VERY reasonable. Now if you think dual 50mm to single 60mm exhaust on a 270-285rwhp engine is optimum... that is your perogative... I think dual 2.25" feeding a single 2.75" would be an easy 10-20rwhp on this application. Headers (properly design like the parts found at www.burnsstainless.com ) another 15-25rwhp. BTW, comparing the results of headers on a Viper vs. any other engine is not good science. OK for guesstimating but the truth is, just like boost levels, power output is combination specific. Power increases represent efficiency changes. The stock Lexus exhaust manifolds are BAD leaving a bunch of efficiency to be had. Even so, your guesstimate of 10% is still a 27-28rwhp gain.

As far as combining or adding results... that again is total package specific. Sometimes a gain is eroded by another mod that would "seem" to help. You use Peter Scott as an example. I have tremendous respect for the way Peter goes about trying and documenting Soarer modifications. That said his exhaust (while much better than stock) is IMHO not even close to optimal.

The whole point here was to honestly and acurrately answer Kreb's question. I believe that is exactly what I have done. I felt compelled to respond to the criticisms of my statements and feel that I have done that also. I am not angry at anyone and do not wish to offend anyone but please do not jump to discredit my postings. All anyone needs to do is ask me how I arrive at any claim I make and I will back it up. I am not perfect and if I accidentally mis-post (like the 450hp/335rwkw that should have read 450hp/335kw) or reference another source that turns out to be inaccurate... I have no problem saying so. I hope this all makes sense and that nobody is taking my responses as insults... they are not. My goal is accuracy, honesty and truthful exchange of knowledge and ideas :D
 
OK we will have to agree to disagree.

When someone proves me wrong by actually achieving these theoretical gains, then I will happily acknowledge you were right, and I was wrong. Until then, I stand by the numbers that have been put down, and not "an optimum this should achieve that". Could've, would've, should've.... all mean "hasn't" to me.

My only problem with your estimates are that none have ever been proven. And every time I have ever seen performance estimates with engines that haven't had the treatment yet, they always come up short. An example of this is your transmission point. You are still telling me that a manual will consume less hp than an auto. I am telling you, that a car here was dyno'd before and after, and had less hp after going to a manual. Yes, there is more to a driveline than the box, but I am saying that this is a focused comparison of the difference between the two components we are talking about. Yes you can say with lighter axles the manual will win, but so what? Attach the axles to the auto and make it a fair comparison. I don't care about documented cases on other cars - I am presenting you a documented case on the auto box in question, vs a W58. Something that you are saying should add 7% - 15hp - actually took a couple of hp.
 
Miles B said:
OK we will have to agree to disagree.

When someone proves me wrong by actually achieving these theoretical gains, then I will happily acknowledge you were right, and I was wrong. Until then, I stand by the numbers that have been put down, and not "an optimum this should achieve that". Could've, would've, should've.... all mean "hasn't" to me.

My only problem with your estimates are that none have ever been proven. And every time I have ever seen performance estimates with engines that haven't had the treatment yet, they always come up short. An example of this is your transmission point. You are still telling me that a manual will consume less hp than an auto. I am telling you, that a car here was dyno'd before and after, and had less hp after going to a manual. Yes, there is more to a driveline than the box, but I am saying that this is a focused comparison of the difference between the two components we are talking about. Yes you can say with lighter axles the manual will win, but so what? Attach the axles to the auto and make it a fair comparison. I don't care about documented cases on other cars - I am presenting you a documented case on the auto box in question, vs a W58. Something that you are saying should add 7% - 15hp - actually took a couple of hp.

Miles, I am doing my best to not consider your responses an attack on my credibility but honesly... your responses are mischaractarising my statements and in such distorting the truth. I request you more carefully consider my ENTIRE responses and not take things out of context.

Drivetrain loss: the sum TOTAL of the conbination of mass, frinction, efficiency, deflection, absortion, harmonics, accoustics, gear multiplication, load and rate of acceleration. You want to use one example of swapping a auto for a manual tranny as PROOF that autos are what... MORE efficient than manuals??? Is this a scientific test with ALL the variables carefully controlled? Here is another for you... if you change final drive gearing, from say 3.42-to-1 to a higher torque multiplying 4.10 ratio the measured power DROPS. IN CONTEXT, my statements and examples are comparing the drivetrain of a luxury car with that of a kit car. I do not know and cannot confirm the drivetrain loss of the kit car but the loss of the various Lexus models are known and the apx 22% that I list is well documented with countless dynos. So, what is your argument? That the kit car cannot, or will not or just has not yet PROVEN it has less than a 22% loss? Please, this is a VERY reasonable assumption. I do not know what the drivetrain specs will be on the kit car above... do you? I am sorry that this estimate is in your opinion "unsubstantiated" but IMHO this is not a tough concept. And frankly, whatever the above specific kit car drivetrain loss is does not conflict with my statements... that being that IF YOU PLACE THE ENGINE in a drivetrain with a 15% loss you will make MORE RWHP/RWKW than is measured in the Lexus with NO OTHER CHANGES. This is irrefutable.

I take issue with you stating that I "claimed" a 7% efficiency reduction with "just" a change to an automatic. I made no such claim. Here is my exact statement from my first post in this thread... "Install that same engine with a lighter drivetrain (manual tranny) more firmly mounted components, and you should get about 15% drivetrain loss"... please carefully note the words LIGHTER drivetrain and more firmly MOUNTED components. This was a generalize statement but reflects the concept just fine.

I take issue with you stating... "My only problem with your estimates are that none have ever been proven"... excuse me? What more proof do you need? You claimed 250rwhp was not possible, here is your quote... "If anyone can show me an NA 1UZ, without some seriously hi comp pistons, putting over 250rwhp, I'd be very very surprised. Maybe with some really really good head work"... I gave you good examples of 250+rwhp with only a MAF and filter upgrade. No, I was not there at the time of the dyno. But, how much RWHP do you think my LS400 needed to run a 14.22 @ 99mph at a 3950 pound raceweight (far far from optmized with a single 1.96" center exhaust pipe)...??? Are you arguing that there is not PROOF that some drivetrains only consume 15% (and in many cases less) power while the Lexus drivetrain consumes 22% (and in some cases more) power???

Miles, I have read many of you posts and definitely have respect for both your knowledge and general way of presentation. I also understand when someone posts something that is surprising... the initial reaction is to request confirmation (some react by accusation and insult)... that said, please consider the source.

If you intend to disagree further... please provide the following courtesy... state each disagreement separately... use a quote from my post to verify accuracy... ask me to substantiate. This is how I feel I have responded to you and IMO shows respect and consideration for the others position.
 
I think what miles is looking for is something like a 300 rwhp NA 1UZ. To my knowlege nobody has done that. Or maybe a before & after showing 40 rwhp difference from a complete header & exhaust system.


As for drivetrain loss, rarely will an auto do as good or better than a stick. On the Supras, where the austo transmission is almost idenitcal to the LS400 & SC400, the 6 speed always does better. Usually is ~18% for the auto and ~15% for the 6 speed.
 
turboandrew said:
I think what miles is looking for is something like a 300 rwhp NA 1UZ. To my knowlege nobody has done that. Or maybe a before & after showing 40 rwhp difference from a complete header & exhaust system.


As for drivetrain loss, rarely will an auto do as good or better than a stick. On the Supras, where the austo transmission is almost idenitcal to the LS400 & SC400, the 6 speed always does better. Usually is ~18% for the auto and ~15% for the 6 speed.

Andrew, yes, I agree with you, as a rule most vehicles with automatics show less rwhp than the same models with standard trannys. The Supra is an example but there are variables. As you know the 1993-98 TT Supra 6M has a larger, heavier limited slip differential than the automatic cars. The 97-98 automatics had LSD as an option but many (most?) did not get it. So, the extra rotational weight is a factor. But, the autos had a higher final drive ratio, 3.77 vs 3.13 for the manuals. As I said above the higher ratio will usually cost power.

I do know that the manual tranny LS1 Chevy Z28s 1998-2002 usually dyno around 290-300rwhp stock vs 270-280rwhp for automatics. These cars engines are identical as are the weight and type of drivetrain except for the automatic tranny. In fact the manuals are more likely to have an available higher ratio rear gear and that would make the manuals dyno lower... obviously the problem in those cars is the tranny. Corvettes are the same way. Actually, virtually all the performance cars that have been available with autos and manuals give the power edge to the manuals.

As far as the example Miles gives of a 5 speed swap... I cannot comment because I do not know the details... identical dyno conditions? engine state of tune? tire and wheel package? same dyno? same fuel? 10-15rwhp swings are not that uncommon with weather changes, correction factors, dyno set up, etc. The difference on an early 1UZFE between 22% and 15% is 15rwhp (using 230hp engine, which is my calculated actual output on the 250 rated engine). Now, if the car was tested with the automatic in ideal conditions and it made say 190rwhp and then after the swap was tested in hot or poor conditions and it made 191rwhp (again this is all speculation) it is easy to state that the tranny swap made only 1rwhp gain... or did it?... in the same situation with the automatic the car may have dyno'd at 175rwp... again, we need much better info for this specific example. For all other examples the difference is consistent and favors the manual for better drivetrain efficiency.

As far as the 300rwhp goal... I agree. Do you agree that the Lexus drivetrain uses about 22%? Obviously you agree that a 15% loss on a manual tranny is realistic. Do you agree that pulling the engine from the Lexus and connecting it to a 15% loss drivetrain it will show more RWHP? Do you agree that the example from this link ttp://www.clublexus.com/forums/sho...&threadid=72625 shows 262rwhp in with the Lexus drivetrain?

I believe the facts show:
262rwhp at 22% loss (235rwhp stock with a 300hp stock engine)
15% drivetrain availability = 285rwhp as is NO other changes.
15rwhp with a decent exhaust = 300rwhp

VERY realistic, not guesstimating, not wishfull hoping.
 
Well, I agree that a getrag would probably be 15%. I don't really know what the stock auto would be. If I had to base off the Supra, I would guess no more than 20%, maybe 18%, but who knows, maybe the Lexus is more. Another factor is wheels/tires. Changing tires can have quite an effect. Going to a wider tire or one with a sticker compound can make a difference. Going to a different weight wheel can have a huge effect on a inertia dyno. Also, the flywheel will affect the dyno result. We quite often see 20+ rhwp increase on with a light flywheel (vs the heavy 38+ lbs one on the Supra). "True" HP really doesn't really change (for wheels and flywheel change), but lower interia on the drivetrain equates to shorter acceleration, so we have better road acceleration (on road and dyno) and higher intertia dyno results.

I hope I can dyno my 1UZvvti without turbos first. With a completly stock engine, AEM EMS (US AEM, not Wolf) tuned to proper AFR and ignition timing, light flywheel, standard tranny, free flowing intake and exhaust, I hope to hit 300 rwhp. Once the turbos go on, that will seem like such a low number :)
 
Firstly JBrady, I am not trying to attack you. My point coming into this was you were throwing out numbers like 450hp, and I really don't see those easily possible... that's like 350+ at the wheels. And the 335rwkw, which you didn't mean to type, I saw as 450rwhp... this is where I started, and this has become a nitpicking contest for lower and lower numbers. My point was the lower numbers were more accurate.

Now with the drivetrain thing, "Install that same engine with a lighter drivetrain (manual tranny) more firmly mounted components, and you should get about 15% drivetrain loss".... can you see how I read that as "a manual tranny is a lighter drivetrain"? To me, you have "lighter drivetrain", and then "manual tranny" in brackets as the sole definition of "lighter drivetrain". If you actually meant changing the prop shaft, axles, diff and tranny, then yes, it will be lighter. I am not trying to make a statement, with my example, about ALL manual/autos. That is exactly my point. I am trying to say "yes, usually a manual is lighter, but it seems that the A341 is already super light in this car". Usually I would expect to see a gain in power from a manual swap, but it didn't happen with the swap from the auto in our cars. As for the dyno variation argument, they are all corrected SAE numbers these days. If you are standing behind that large a potential variation, I can argue that Peter's headers possibly decresed the power output of his car? I think if we are looking at dyno numbers, we have to believe them to some extent. When we see a change we don't expect, we can't just discount it. I should know soon enough how the manual will go - on track to change mine to a R154 in 2 months. Finally!

What I was trying to say with the drivetrain was, I thought you were asserting a swap to a manual (and that's all), would yield 7%. My point was "don't be so sure, it didn't happen for a Soarer". If you are actually saying "change to lighter axles etc" then yes, you could find that 7%. I think the problem there was I read your post differently to how you intended it to be read.

Lastly, all I am trying to say is, numbers are numbers. They are all well and good. I did not know that anyone was putting down 250+ with a 1UZ - if you are, that's excellent. The 262 car is a 3UZ, and I read "Borla exhaust". What's wrong with the Borla? But in the end, I think all the estimates need to be taken with a grain of salt, until someone actually shows a 250 1UZ graph, and a 300 3UZ. Until then, aren't we just guessing what each mod will give?
 
Miles, good, we are on the same page...

We agree that there is at least 7% possible gain going from a standard Lexus drivetrain to a less parasitic one... I do not know what type of drivetrain the kit car being considered has or will have but it is likely to be less parasitic than the stock Lexus.

As far as 1UZ vs 3UZ... The 3rd link I gave was for a 1UZ making 249rwhp reportably stock. Down in the thread there were additional reports of stock ones making 230-240rwhp and SRT + exhaust cars making 240-246rwhp. These were just a few examples as there are a bunch more out there.

As far as weather and dyno'ing... especially on OBDII vehicles the hot weather can trigger more ignition retard and other factors that reduce output on modern computer controlled engines. Simply correcting for air quality does not take this into consideration. My car runs a 14.5-14.6 in 85 degree weather but ran several 14.2s in 45 degree weather. That is 20-30hp difference. I don't think a 40 degree difference is going to show that much of a variable on the correction tables. Maybe someone can speak to this. So, yes, air quality can cause big differences in dyno runs even after corrections.

On the exhaust, when GS400 (or virtually any Lexus in the USA anyway) says exhaust mods... they are almost always talking about just a muffler upgrade. Since these cars have decent flowing rear mufflers stock and the restriction is in the manifolding and y pipe, just changing the mufflers does not constitute upgraded exhaust from a performance consideration. Fancy tips and louder sound but no power.

There have been dynos posted of 1UZFE cars making 250rwhp with just the MAF mods. These are of course the 1998+ VVTi engines. The 3UZ dyno of 262 is high but 255 is common. So what needs to be taken with a grain of salt. Do you not agree that you can adjust these numbers for a better drivetrain and get a jump from 250 to 272rwhp (1UZ) and 260 to 283rwhp (3UZ)... ? Agreed?

So now we are theorizing on the possibility of adding 28rwhp to the 1UZ and 17rwhp to the 3UZ. I am suggesting this can be done with bolt on mods. I think just a well crafted exhaust can do it. Certainly exhaust plus and ECU to raise the redline to 6700rpm would do it. This is my assertion. Do you feel it is irresponsible of me to make this claim?

As far as my statement about 450hp/382rwhp being possible with the 1UZ/3UZ... I stand by that as well. That would take much more effort (headwork, camshafts, manifolding, higher compression and contoured pistions, ECU tuning, 8000rpm, etc.). Frankly, I don't see this as a problem. Consider how much power some have gotten from the Ford 5.0 engine. You can say "prove it" but the technology is already proven elsewhere. It would only take some hard work and money to do it.
 
Miles,

How many extra "untapped" horsepower does the Viper have as a percentage of it's current horsepower? Be honest without pulling the engine down.

Then ask yourself the same question of the 1UZ-FE.

The answer will explain why you are a member of Lextreme.
 
Rod,
if we include heads, cam, intake, exhaust and tune, Vipers go from a stock 415 to 575-600. So, somewhere between 40-50%.

I am a member here because the 1UZ matches my budget, and hasn't been done before.

JB,
the 450 with rods/pistons/big$ I don't doubt. It has already been done in NZ.
 
Miles B said:
Rod,
if we include heads, cam, intake, exhaust and tune, Vipers go from a stock 415 to 575-600. So, somewhere between 40-50%.

I am a member here because the 1UZ matches my budget, and hasn't been done before.

JB,
the 450 with rods/pistons/big$ I don't doubt. It has already been done in NZ.

Miles... since we have cleared up any confusion over my statements regarding rwhp potential and automatic tranny concerns... it appears that we are in complete agreement. I am glad we had this discussion as it puts out some good information for everyone to consider.

Regarding the Vipers... is the 415rwhp what the new 500hp engines make or the older 450-460hp engines? 17% loss on 500hp, slightly under 10% on 460hp and under 8% for 450hp. With the large heavy components and IRS... I would lean towards the 17% on 500hp.

You also state the best exhaust you have seen on a Viper (headers to tailpipe) was good for 45rwhp so I guess the other 140rwhp (600rwhp total = 185rwhp gain less 45rwhp) comes from the combination of headwork, camshaft, intake manifolding and tuning. Do you happen to know how much this exhaust increases and otherwise stock Viper engine? Honestly I have not seen the 500hp Viper exhaust manifolds and system. My guess is that the factory manifolding is not bad (the Lexus manifolding is bad). I will try to find some pics on line.

My thoughts are that the Viper exhaust gain potential is in the neighborhood of 7.5-9% (depending on tune) over its factory exhaust. Considering the Viper probably has a more efficient exhaust stock than the Lexus designs... and considering that the 4 valve head design favors high rpm vs. the 2 valve designs... it would be very reasonable to suggest there is a larger percentage available to be gained with exhaust technology in the Lexus V8... do you agree with this theory? Now, the number is hard to know for certain but if the Viper has 9% and the Lexus "should" have more... we can certainly start with the 9% upper end of the Viper as demonstrable. Take our above 1UZFE example of 250rwhp in a Lexus, 272rwhp in a 15% loss chassis, we can then see 272 + 9% as a very reasonable number for that combo with a good effort exhaust (probably more but this is reasonable) for a total of 296rwhp. What do you think? If we consider how very bad the Lexus exhaust is... and assume a decent stock Viper exhaust... and compare the potential of the 2 vs 4 valve head engines... I would not be surprised at all to see 15% potential or even more. 15% would give 312rwhp. Of course these are based on the 4 liter 1UZ... the 4.3 liter 3UZ would be 262/285/310/327rwhp respectively. As you said, parts need to be actually built to show design success but I have great confidence that the Toyota engine has more upward potential (as a percentage) than the Viper engine.
 
Nope, 415 comes outta the old "450hp" 488ci motor. My guess is they just underrated it?

I don't know about the new exhaust on the 505/500, but the 488/450 had two generations of headers.. the second was slightly better - adding it to the old generation yielded about 8-10hp. The A+ exhaust system was on an otherwise stock car - it went from ~415 to ~460 from memory.

Most of the gain comes from headwork. I believe most of the high 500s cars got about 40 from exhaust and intake, 20 from cam, and the rest from heads and tune.

I have no idea if the UZ would be better than the Viper motor with exhaust. I believe, for a 2V motor, they put a hell of a lot of work into designing the heads. Who knows what goals the Toyota guys had in mind, I know the Viper team was only after performance. Mileage is absolutely disgusting on that car.

I'd really like to see what would happen if a decent tuner, experienced at head and cam work, took on this motor. I've seen some motors produce very little after a lot of head and cam work... others like the Viper just go crazy..
 
Who knows what goals the Toyota guys had in mind
Everything but outright power.

Basically efficiency, smoothness, and quietness.
Power would have been at the bottom of the list
 
turboandrew said:
Well, I agree that a getrag would probably be 15%. I don't really know what the stock auto would be. If I had to base off the Supra, I would guess no more than 20%, maybe 18%, but who knows, maybe the Lexus is more. Another factor is wheels/tires. Changing tires can have quite an effect. Going to a wider tire or one with a sticker compound can make a difference. Going to a different weight wheel can have a huge effect on a inertia dyno. Also, the flywheel will affect the dyno result. We quite often see 20+ rhwp increase on with a light flywheel (vs the heavy 38+ lbs one on the Supra). "True" HP really doesn't really change (for wheels and flywheel change), but lower interia on the drivetrain equates to shorter acceleration, so we have better road acceleration (on road and dyno) and higher intertia dyno results.

I hope I can dyno my 1UZvvti without turbos first. With a completly stock engine, AEM EMS (US AEM, not Wolf) tuned to proper AFR and ignition timing, light flywheel, standard tranny, free flowing intake and exhaust, I hope to hit 300 rwhp. Once the turbos go on, that will seem like such a low number :)

Andrew, you raise some good points. IF a car gains 20rwhp with a flywheel... that means that the car now has 20rwhp more to accelerate. Of course the more the weight differential and the faster you try to accelerate the larger the gain from reduction in rotational mass. Tire/wheel mass is rotated slower than the flywheel but weighs more so as you point out it does make a difference. Friction of tire to road surface is another point of efficiency. All of these things are examples of drivetrain loss variables. Any way you cut it improvements in drivetrain efficiency shows more RWHP and performs accordingly.

Regarding the Lexus drivetrain loss. You can decide. I feel the original 1UZFE was over-rated and is more like 230-235hp. Even so, 230 - 22% = 179rwhp... most stock early 1UZ LS400s show just about that. If the loss was only 20%... working backward shows an engine making 224hp. 18% would mean the engine was only making 218hp. If you believe the factory rating of 250hp the drivetrain must loose over 28%. I think the 22% is reasonable for the early cars and calculates pretty well on the later cars.

BTW, what do you intend to install your VVTi engine in? I am in Houston and would love to see what's going on some time.
 


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