Twin Turbo T25 cast iron turbo manifolds

[autronic]

Hi.

Been a while since i have been around but, just as I thought I was out I get dragged back in.

A friend of mine is building a kit car, a cobra mk4 replica from Gardner Douglas gdcars.com
and he is using a 1UZ-FE engine with twin turbos in it.

As a joke I said I would get him some twin turbo cast iron turbo manifolds and he jumped
on that, imagine my chagrin when I found out that nobody makes this.

So, for the last year I have been searching for a foundry that is willing to make some, I have
found a foundry in Turkey but the minimum order is 10 pairs, so 20 manifolds in total.

I have tested some early 3D printed versions of the manifolds in his kit car and they are as a
tight fit as I can make them, there is no space in that engine room!

The design of the right side manifold is done. There is still some work to do on the left side
manifold.

The center of the left T25 turbo flange is placed 80 mm behind the center of cylinder 2 and 3,
the center of the right T25 turbo flange is placed 59 mm behind the center of cylinder 2 and 3,
this is done to compensate for the 21 mm offset between the sides.
It also places the turbos symmetrical VS the block and the engine mount flanges.
I looked into placing the turbos in the center between cylinder 2 and 3, but the outside of the
compressor housing comes into conflict with the engine mount flanges on the block.

The two turbos we have tested is Garrett GTX2867R clones, with T25 inlet flange and integrated
wastegate.
I think Mitsubishi TD04HL-19T turbos should fit, it looks like they are slightly smaller than the
Garrett ones.

The alloy will be EN-GJSA-XNi22/S-Ni22/S-Ni22 cast steel alloy, an alloy often used for turbo
turbine housings.

Is there any interest in this?

 

[autronic]

Forgot to post how much this will cost.

10 manifolds for each side looks to be €265 each, so 20 pairs will be €530 for a pair + freight.
This price is not final, this is what the foundry have given me as an offer.

 

[Lextreme]

Interesting!

 

[P Bateman]

I can imagine there isn't much room around the engine in a Cobra body - but there must be a heap underneath if you can squeeze in twin low mount turbos under each side! In the majority of cars with a turbo 1UZ, the turbo/s are placed in front of the engine due to the positioning of the engine mounts, steering shaft, alternator, AC pump etc.

The LS engines that Gardner Douglas offer in their cars are much more compact than a 1UZ plus they don't need turbos to make +400hp.

These manifolds are a great idea but I'm not sure you'll get many takers on low-mount configuration.

 

[autronic]

Did some quick and dirty 3D printing of both manifolds.

When we was testing in the car I usually just printed the two exhaust ports
closest to the turbo flange.

I only have a few pictures of the in car tests + they are an early version
with turbo flange between exhaust port 2 and 3 and the turbo flange
needed some adjustment.

 

[autronic]

P Bateman:

Turbos mounted so low you need an external electric pump is something I will
not use, you insert an extra point of failure here.

This design places a Garrett or Mitsubishi turbo so the turbo will drain back to
the sump without any issues.

I agree, front high mounted turbos would be better but making some that will fit
in all applications is an issue, also it is not suitable here, due to space restrictions.

That said, it is possible to design a manifold to end in front of the front exhaust
port with a flange + have the head exhaust bolt pattern for both sides on this
manifold so it can be used on both sides.
Again it cost money to get something like this manufactured.
If you have takers for 10 of these, 5 pairs, let me know and I will see what I can
come up with.
If you have takers for 20, 10 pairs, I can design 2 different manifolds that can come
further forwards and up.

In the case of this Gardner Douglas mk4 the 1UZ engine was chosen to suit the
rules here in Norway, an LS with 400 hp would be an difficult to get approved by
the Norwegian DOT, it's easier to use an 1UZ with 2 tiny T2/T25 Saab 9000 turbo
units and around 320 hp when it's being approved.

This car will also use a heavy transmission, a BMW F82 M4 DCT. Everything that
have to be manufactured, engine mounts, all bracket, an extra engine subframe
and the transmission subframe is made as heavy as possible but there is a limit
to how far you can "stretch" this.

The rules here are strict, you can have 20 kW (27.2 hp) for every 100 kg (220 lbs)
car weight. You can add lead BUT only up to 5% of the cars total weight and they
will check the weight of it + see where it's placed and how it's mounted.
So an lightly turbocharged 1UZ is "easier" in this application.

 

[autronic]

Hmm, I think it's also possible to add an flange and port for an external wastegate
to the manifold.

Placing it where all the ports meet, opposite the T25 flange should work out fine.