2.0 "Nubie" Turbo dyno results

pontiacjeff · Post by **pontiacjeff** » Thu Oct 21, 2004 1:33 am

Actually, it's a '88 Grand Am turbo LT3 with a DOHC swap. It's a fully-built 2.0, stock 60K-mile 'woo head.

Bottom line: 240whp/275wtq, 16psi. Read more about the engine and tuning here:

http://lt3engine.board.dk3.com/2/viewtopic.php?t=160

Read about the car here:

http://www.geocities.com/pontiacjeff/88TGA.html

The link from the car pages to the DOHC swap pages isn't working so use this:

http://www.geocities.com/pontiacjeff/DOHCswap1.html

daewooluvr · Post by **daewooluvr** » Thu Oct 21, 2004 2:02 am

I'm so jealous, you rock.

Any ideas on what exactly happend with the T20SED to burn it up?
Is it only because you leaned out or did something let go?

pontiacjeff · Post by **pontiacjeff** » Thu Oct 21, 2004 2:26 am

I blew the head gasket so I replaced it and it still only had 90psi compression and was sucking water into the cylinders from somewhere. I think I broke some rings. Like maybe all of them. It might have split a cylinder, too.

The new "old" GET block is not as stiff, it lacks some re-inforcements the newer T20 blocks have. But it seems to be holding up quite well.

I think over 15psi on the 9.5:1 T20SED is not a good idea. Especially with the cast pistons. In tuning the new engine, I have leaned it out as bad or worse than I did the other one with no adverse effects. It is only 8.0:1, but has forged pistons. I am making the same hp with the bigger 20G as I was with the smaller 18G, but that's with 1-1/2 points LESS compression. I can now run more boost than I could before. I almost think I went too big with the 20G, but I have yet to really try it with the exhaust cam advanced back to +4.

Post by **PrecisionBoost** » Thu Oct 21, 2004 2:56 am

I had a customer test my C20GET block with a very expensive hardness tester and it showed the cast iron block to be quite hard... and the crankshaft gave almost the exact same number.

Originally we were trying to determine if the crank was forged or not but he figures it's the same as the block....cast iron... but harder than most cast iron he typically tests. (may indicate a higher content of other natural elements such as Silicon, Carbon ect )

I was saying to GsiTurbo that perhaps the new T20 engines need the extra ribbing to make up for a lower grade of cast iron.

My C20GET has 210,000km on it and it has the same wear as my T22SED with only 50,000km.

I've been thinking about using my C20GET block with my Daewoo head as well but I think I'm going to use 8.6:1 pistons.

The only difference between the C20GET/T20SED is that the T22SED has a slightly higher deck.... about 1cm.

All bolt patterns are the same and they look identical without carefull measurement.

One slight difference is that the oil dipstick is located on the left side of the exhaust manifold instead of the right.

daewooluvr · Post by **daewooluvr** » Thu Oct 21, 2004 12:28 pm

So what you all are saying is that the T20SED block will fail in time with 250+ whp?

Suppose we ran 8.6:1 compression and forged pistons, would this still be a problem?

If so would sleeving help?

Post by **PrecisionBoost** » Fri Oct 22, 2004 4:24 am

I think the stock block is good for more than 250hp.... I think the failure was due to the high compression pistons.

I think the C20GET block would be good for at least 350hp if not more but I have no idea what the T20SED block is capable of.... who knows it might be more than the C20GET... until someone breaks one it's hard to say.

I was just saying that the C20GET seems to be very hard compared to a standard iron casting.... I haven't tested the T20SED so I don't know how it compares.

I personally wouldn't push the stock high compression pistons above 7psi witout other modifications.

If this engine had been tuned to run on racing fuel it probably would have withstood 15psi or more but if you want to stick with premium I think it would be hard to go over 7-10psi unless you have everything just perfect.

I'm saying that you need the right sized turbo running at it's peak efficency, a correctly sized intercooler and a hell of a lot of tuning on the dyno to ensure that you don't get detonation.

I'm going to run 8.6:1 as this is very close to the C20LET which had a 16V head.

Sleeving would help but I don't think it's needed unless you are looking to make really high horspower ( say 400hp or more )