Just wondering. I want to do some sort of swap soon and I'm checking things out. Thanks!!

 

Do you have a 350 or a 305 in the car now?

 

Doesn't matter, same system on either one (except for injectors), and it will be restrictive.

You absolutely need shorter, fatter runners to get the RPMs up to the ZZ4 range and increase flow. Then, the plenum must be ported. Either port the stock base, or get a Big Mouth intended for Vettes (for the EGR provision). 52mm TB a good idea; AFPR, and 22 lb injectors (if you have a 305 now - if 350, you already have them).

Figure on some PROM work.

 

I have a TBI 305 right now. If I use a stock 350 TPI unit how much will the 355 HP rating fall?

 

A ZZ4 is merely a 350. It has the same heads as a Vette L98. Look at what a Vette with a L98 puts out, that's exactly what a ZZ4 with TPI will do.

That said, when I do the math, it looks to me like TPI will cost you around 100 HP off of the motor's potential.

305 and 350 TPI are identical in every way, except the 350 one has 22 lb/hr injectors in it instead of 19, and the PROM is a little different, and they use different knock sensors. Don't waste your effort over trying to differentiate between them, it's the system that counts not what motor it was originally installed on.

 

It's a bit of a stretch to say "ZZ4 w/TPI = L98". The cams are different, and the ZZ4 shortblock is much better than L98.

But, I do agree that the HP loss with a stock L98 TPI would be substantial vs. the advertised 355 HP of the ZZ4 when carb'd.

 

In general, ZZ4 cars with the TPI run mid 13's, fastest I have seen a ZZ4 engine run with any sort of induction is 13.2, so its not that bad using a TPI on one IMO.

 

When i bought my fastburn crate motor i asked the same thing and the guy over at scoggin-dickey said that the motor is set up for carb use so if i were to put the stock unit on it would drop power dramaticaly. I believe he told me around 325hp or so. I bought a speed demon for it, sat on the idea for MONTHS, and i just recently purchased the miniram and hot cam for it. I will be doing the swap in the next couple of weeks so i will see how it turns out! I wouldn't recomend putting the stock unit on it at all.

 

ZZ4 is basically a L98 built with the best stuff GM had, and a mild cam.Rated at net HP as cars are now,a ZZ4 is probly 300-320 hp,
250-270 RWHP with TPI, with an auto.Mine runs 13.700 @102 ,blistering the tires hitting 4th/overdrive about 100 feet before the lights,to get its best MPH.

 

How do you think the Super Ram setup would do on the ZZ4? 52 or 58mm TB? Obviously that setup is going to be much better than the stock TPI intake system.

Also, just out of curiosity, I noticed that the ZZ4 motor is tagged as being designed for pre-76 vehicles. What exactly does this mean? After all, it seems to be a fairly popular swap into our cars.

Matt

 

It means the dealer won't put it into one of our cars.

EGR is one hurdle to cross - no exhaust cross-over passages in those heads, so exhaust has to be plumbed up to the intake for the EGR valve to work. Dealers don't like doing that kind of work. Anyway, that's why I said use a Vette base earlier.

Of course, if you have a carb'd auto tranny 3rd gen, you can get the HO 350 conversion kit, which IS emissions certified...

Oh, yeah, we're talking TPI. Never mind...

 

So what do you have to do to put the TPI on and have it fully functioning? Just kinda wondering, cause I hope to do this swap in the near future. Do many non-GM shops do that kind of work? Thanks

Matt