GT6 GT6 engine in a TR6

[skikir]

I have a '72 TR6 with a GT6 engine in it. Didn't realize it at the time I bought it as a project. I looked up the HP ratings and the GT and TR sixes are just about the same. Tourqe may be different. I have a couple of spare engines one of which is still in good shape which I plane to put in some day because the engine in my car now rattles when it first starts and oil pressure is low but it runs pretty good for now. In the mean time I want to put on a few extra goodies like Good's TRIPLE STROMBERGS and a header and be able to install them on my TR6 engine later.
The GT6 engine has the dual exhaust manifold of the latter TR6s and of the engine I want to install. Does that mean I can put the new intake and exhaust system on now and transplant later?
A mechanic friend mentioned the best thing is to put a GT6 head on a TR6 engine. Is there a difference between the heads or is it a matter of compression ratio?

 

[aeronca65t]

I can't advise you on the interchange of TR6 and GT6 parts, but I can say this: if your engine makes a rattling sound on start-up and has low oil pressure, you should not try to add speed parts to it....this will only kill it sooner (probably much sooner!).
If you want to spend some time doing something useful to your engine, you could replace the thrust washers. They are weak spot in these engines, are cheap and easy to replace and if you put it off too long, your engine will destroy itself. I'd replace rod bearing at the same time (again--- pretty easy, cheap and super-important).
For "how-to" info, type "thrust washer" into the "Search" area of British Car Forum....they've been discussed a number of times in the last few years.

 

[Simon TR4a]

I agree with the above but would add that using a GT6 head on a long stroke block will give a compression ratio which is much too high unless a lot of material is removed from the inside of the combustion chambers to lower it. Better to stick with the original head and have it milled to get the ratio you want.
Valve sizes differ from early to late TR6 engines and ports may be spaced slightly closer or further apart; I think there are three different castings in all, so the exhaust manifold from one engine may not match another exactly.
I think you are right that torque would be much greater with 25% more displacement, this should be very noticeable when you change engines.
You may well find there is a market for your GT6 engine, they are popular for upgrading Spitfires to "Spitsixes"!
Simon.

 

[skikir]

FYI or if your on a Trimph Q&A game show; After lusting again on Good Parts Triple Stromberg web site again I noticed he had a set of intakes for GT6s too so I thought I'd ask the expert and wrote:

This one's a bit odd. I have a TR6 I want to put a set of triple Stromsburg's on BUT I have discovered that a previous owner has put a GT6 engine in it at some time. The engine is a bit tired and I have a good TR6 engine I will be fixing up and transplanting into my TR6 later. In the mean time, Id like to put your intakes on in my car. I am familiar with TRs but not so much with GTs. When I bought the car I did not even think the engine was different (buyer be ware) and assumed it was a '72 since it was in a '72 and has the dual exhaust of that vintage. Will a TR6 wide intake fit a GT6 wide intake IN a TR6 so I can buy now and transplant later?
>
>Skip

To which he wrote.

Yes, it will fit.

Richard