Garrett Emails

-----Original Message-----

From: John Clark
Sent: Monday, September 20, 2004 11:58 AM
To: BS
Subject: Garrett Esprit V8 - Help!

Hi, I came across your entry below on the Yahoo turboesprit message board...

I'm building a tuned type 918 V8 Esprit myself ( ) - using forged Mahle pistons (Keronite coated), re-worked/ported/polished heads, an ex Le Mans Lotus GT1 plenum and a specially fabricated twin chargecooler, based on the Lotus Carlton unit. I'm just getting to the stage of the turbo upgrade (the final piece of the engine tuning). I'm looking to fit Garrett GT28RS turbos, with .64 A/R - I'm expecting power of 600 bhp, so the standard T25s will be insufficient.

I've got problems though, because the GT28RS do not fit - as I suspected the standard exhaust manifolds do not give sufficient clearance from the bell housing and I'm also worried about clearance to the chassis tubing.

I noticed in one of your photos that the Garrett V8 has a turbo upgrade - witness the 5 bolt exit from the turbine/wastegate housing - Do you know what turbos they are using? and if the manifolds (you call them headers, right?) are different?

Failing this, do you know any contacts within Garrett that might have knowledge of the work done on their engine? I'm thinking of totally repositioning the turbos and having manifolds fabricated, so you could help save me a lot of time and expense!

Many Thanks,


-----Original Message-----

From: BS
To: John Clark
Subject: Re: Garrett Esprit V8 - Help!

The Engineer contact there is Rob Simmons and his boss is Andrew Nunn. Andrew heads up the North America side of Garrett Air Research.

The gentlemen who built this beautiful V 8 is KW and he heads up the Hypersport race team that races the Garrett Esprit. He will know which turbo he is using for the race car and he did all of the exhaust plumbing so he will be able to answer the header questions.

Their race show web page is They are building Esprit race cars using the new Garrett roller bearing turbo's. they had to cut a notch in the block to fit one of the turbo's but that didn't hurt anything. They are producing a ton of power at the rear wheels, but not as much as your car.

They do have the Lemans Race Esprit in their shop , the former Zenardi car that he raced back in 95 I believe.

Where are you located ? where are you going to race your car ?

Kirt buildt the Esprit race car and is actually working on the 2nd car. I ssaw it test last weekend and it goes like crazy. Kirt did all f the turbo plumbing and is a master at that. The car is extremely fast.


----- Original Message -----

From: KW
To: John Clark
Sent: Monday, September 20, 2004 10:37 PM
Subject: Esprit V8

Hi John.

As the photos show as sent by Brian, GT25R's do fit, albeit that the RH bellhousing must be relieved for the fitment. We had to do this per the rules. An easier arrangement would be to choose a turbo without an internal wastegate. This would allow more clearance, as well as better flow with the wastegate downstream. Good luck!


----- Original Message -----

From: "John Clark"
To: KW
Subject: Re: Esprit V8
Date: Tue, 21 Sep 2004 20:03:53 +0100

Hi Kirt,

Thanks for your reply - so you are using GT25Rs, I see. I thought they were a change from the T25s, from the 5 stud exits..

Well it's no surprise I'm having issues fitting GT28RS, if you've had to releive the bell housing to fit GT25s! So, you're using standard headers (manifolds) are you? - they do look standard - Is this a mandatory in the formula rules?

Have you dyno'd the engine with the GT25Rs?

I'm now wondering if I could lower the turbos and bring them inwards to the rear of the bell housing - that way I could just get a adapter made up, to bolt between the standard manifolds and the turbine inlets.

Two issues concerning me here though

1) Is there an optimum distance for the turbine to sit from the exhaust ports? What's the max to keep under? should the adapter be fabricated with 2 internal ports to keep the cylinder pairing close to the turbine inlet (important for pressure pulse - keeping the turbine spooled, I beleive)?

2) Is there an issue with the oil return if the turbo is below the return to the sump? The height of the entries into the sump look likely to be above the sump oil level, is this right?

I was hoping to ship the engine to the dyno for mapping first, but right now I'm thinking of dropping the engine into the chassis and mocking up the turbo positions for manifold adapter fabrication, exhaust exit route etc.

Your advise (and that of Garrett guys) would be very gratefully received - I want confidence in the lubrication of my new turbos!

Many Thanks,


----- Original Message -----

From: kirt wightman
To: John Clark
Sent: Tuesday, September 21, 2004 8:13 PM
Subject: Re: Esprit V8

I can't address pulse reversion points and etc. We have to use the stock manifolds as per the rules. Be careful about lowering the start to get below the gravity-fed oil drainage port allowed in the oil pan. Also, be aware that you will need to restrict oil flow/pressure to the turbo, as the roller bearing units need much less pressure than the stock unit.