Us Non-Turbo guys read this section too
Hey DSMspeed,
I have a 99 GS turbo. Hahn Racecraft Stage 2.
Other than some small tuning issues, I have not had any problems at all with my turbo kit. I have the stock pistons and rods, and have been boosted for over 6 months now.
The way the turbo gets its oil is through the oil sending unit on the back of the block. You tap into that with a SS feed line which lubricates and cools the turbo. The turbo does not come water cooled, but can very easily be made to tap into the coolant lines.
95-96 RS and GS models have been known to have especially weak headgaskets, but 97-99 are very strong. That is really the only "problem" with the 420a. Get a 97+ and you are all set. This problem however is very rare even on the 95-96 models.
The 420A responds very well to boost, even with its 9.6:1 compression ratio. If you want to rebuild the engine with forged pistons and rods, add injectors and an SAFC, you will see 15+psi on pump gas with 8.8:1 compression, which will be good for low 13s-high 12s. All of this with a stock head, intake, valvetrain, etc.
Yes, it IS easier to start with a GS-T or GSX, and mod from there... here is my small list of pros and cons:
4G63:
Pros: ECU that understands boost, engine that can support 400+hp with stock internals, much larger aftermarket, AWD offered, huge wealth of knowledge (Talon Digest, dsmtalk, Buschur, etc).
Cons: Crankwalk, MAS, tranny issues, more $$ for insurance, costs more to begin with, heavier.
420A:
Pros: No crankwalk, no MAS, lower insurance, great tranny (very few problems ever reported), you get all the aftermarket parts at once with the kit (manifold, 16G or T3/4, dp, IC, IC pipes, etc), the car is anywhere from 200-400lbs lighter than the GS-T/GSX respectively, the GS is basically the exact same car as the GS-T other than the engine/tranny (which means all aftermarket parts for the GS-T work on the GS other than those engine related.)
Cons: ECU that cannot read boost, weaker internals, small aftermarket (basically just HRC), turbo fuel system runs at ~110psi at WOT, no AWD offered.
I am sure there are more, but you get the picture.
One of the ways I look at it, is that if you want the AWD, go for a 1G. If you want the AWD with the 2G body style, go for a GSX or TSi AWD, but watch your crank. The biggest "problem" with the 4G63 is crankwalk, which honestly doesn't happen as much as people fear. However, once it happens, it is not fixable and is very likely to happen again and again. The biggest problem with a turbo 420A is that you could blow the engine. This is fixed once, and that is it. But this too does not happen often as long as the car is properly maintained and tuned. It costs $850 dollars for JE forged pistons and Eagle forged rods, including rings for the 420A.
If you would like some more information, go to
http://www.2gnt.com/forums.html. There are a lot of turbo 420a guys there that are a lot faster and know a lot more about this engine than me. Or you can call Bill Hahn Jr. and talk to him.... he will talk to you about this engine until your ears fall off
By far the most knowledgeable person on the topic.
(wow, this got long... I'll shutup now.)
By the way, I don't hate the 4G63. I actually really love the engine. I just happen to really like the 420A as well. I own a 99 GS and a 91 GSX.
My engine:
