Turbos w/ carb

[kridgley]

Hey guys:
I dont know a whole lot about turbos and such ... but Im probing into the possibilty of putting them on a new ZZ4 crate from GM. I however want to keep it carbed. Can this be done? If so, what other mods does the ZZ4 need before it can take a turbo or two?

Thanks, Kevin

 

[lov-n-life]

Interesting

Short answer... yes... Would I ever do it.... Shorter answer... NO!:crazy Trying to get a fuel/air ration mixed correctly, consistently through the power curve, would be a nightmare. Not to mention I don't know that there is an air filter housing designed for it (one that sits on top of the carbs) for Chevy motors. The other route, probably a better route, would be an air box in the air stream before the turbo. Still, that is alot of custom fabrication. Also, if you take a look at carburated cars that had turbos, such as the Porsche 930, you could end up with alot of turbo lag and if the boost hit while the engine was under load in a corner, you would get to watch your tail pass you! Best bet would be supercharger (similiar air box issues, but no turbo lag) or a blower. The later probably being the better option as I'm sure there are already kits readily available.

 

[Evolution1980]

I have the ZZ4 in my car and have been kicking around the same ideas. However...I haven't decided to do it...yet.

First, the natural compression ratio of the ZZ4 is 10.5. That's a bit high to be force feeding any more air. Not to mention the amount of custom fab work you'd likely have to do for turbo(s).

My first route is going to work on the engine itself. The ZZ4 is a great starting point to building a ZZ430 (430HP and 430 Tq) It's the ZZ4 with the GM 385 Fast Burn heads, the LT4 HOT cam, and 1.6 rockers. The torque is only 25 more, but the ponies go up by 75. The compression ratio then comes back down to a more manageable 9.6. That would be [more] reasonable then for turbo or supercharging.

I just now did some checking around. You could likely buy the parts new on ebay for under $600.

 

[tomtom72]

Hi Kevin, There was a guy that did alot of basic research on turbos for GM about 20 yrs. ago and the company name is Gale Banks Engineering. I saw a spot on speed channel where that Co. has a kit for chevy SB & BB motors. Also didn't Calloway do turbos on vettes? I would check them out because there are speciality bits of knowledge needed to do a system correctly. Just my 2 cents. Tom.

 

[Evolution1980]

Also didn't Calloway do turbos on vettes?

Yes, he did. In fact there's entire forum here on CAC devoted to it (It's the Callaway section under the C4 forum.)
The difference is that all his cars started with some type of fuel injection setup, whereas this is a carbureated application. Also, the base engines were lower compression to start.

 

[kridgley]

thanks for all your responces guys, i'm thinkin niow how much its going to be putting them one, and looking the other direction. The idea of a blower sounds more practicle, I'll look that route.

kev

 

[Twin_Turbo]

Sure it can be done, either blow through (banks systems) or draw through (martin turbo sys)


There are some things you need to modify on your carb, there is an article on the net somewhere about modifying a holley for turbocharging/supercharging. Do a search on it, it's a very good read (step by step intructions)

Turbo lag really is not a problem in a V8, especially if you use 2 smaller turbos. Small 4 bangers have turbo lag problems, if you stick to a sane power level and select the proper turbo you won't have any lag problems (I'm not talking super large 1000+HP single turbo apps or big duals for even more oomph)

The supercharger certainly is not simpeler, the modifications to the intake system and the block are very similar, the only area where it's easier is the exhaust system.

The ZZ4 will need a lot of work to handle the power. First of all the L98 heads are too thin in the deck area and the chambers are tiny, this means you will need seriously dished pistons. You'd need new pistons anyway because the stockers are hypereutectic and won't stand up to serious cylinder pressures. You will also need a special grind cam. Reworking the heads is an option, if you stay udner 450Hp or so (kind of a waste though since that level is easily attainable without a supercharger/turbo)

A CR of 9.6 is way too high, keep it under 9 and close to 8.5 if possible. Getting it down any further will increase the turbo lag (very low cyl pressures and a big loss of torque)

Another area that needs seriosu interest is ring gap, you need to run a wider gap because of the higehr comb. temps (higher cyl prssures) and a high volume oil pump is not a luxury with the added oil consumption of the turbos. A drain system with large ID hoses hooking up to the pan with no horiz spots is also needed. For the ebst protection of the turbo an accumulator switched to discharge on shutdown is a great way to keep the turbo's oiled after engie shutdown (the turbo will spool for quite some time)