I was wondering if anyone had an opinion on using TPI on a new ZZ4 crate motor from GM? I am considering getting one but want to keep the car fuel injected for daily use. Thanks, Rob.

 

It'll work...you'll just need to change the manifold. That's because the manifold that ships with it is set up for a carb. Another thing to keep in mind, if you're going from a 305 TPI, you'll need to change your injectors to 22/24 lb injectors. Also you'll pretty much NEED to port the plunum and TB or else you'll choke that motor. If you'll have some extra cash left over, I recommend you change the cam and port the heads that come with it. You'll have a 300 RWHP car then easily! Just dropping the engine in the way it comes from GM and putting your stock TPI back on it you'll pretty much only have GM stock 350 performance, maybe slightly more. So in other words, at least start modding the TPI a little if you're gonna put the ZZ4 in.

 

Well, i wish it was that simple. This car is currently a TBI 305. I picked up a complete TPI setup and am having it checked/modified to make it work. It was off a 350 so most of it shoud be ok. I guess I should look into doing a little porting before I go to the trouble of bolting everything up. What kind of cam change? I'm going to drive this car most of the time so I don't want it to be tempermental, but at the same time I want to try to get as much out of the engine as reasonably possible. Just trying to get organized for getting it finished. Thanks, Rob.

 

The ZZ4 cam is fine. I'm running it and the ZZ4 heads in my car. The big thing is porting the intake, like he said, or getting an aftermarket intake. I also ported my heads. It made 280 HP and 370 TQ at the rear wheels so far.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies

 

you haven't mentioned if you have or are going to use headers. Headers would be a must have item too.

 

The headers are already in place. I used coated SLP's and 3" system all the way back (single Pipe). This car is almost done, I saved the engine for last. Other mods are T56 tranny, PST front end kit+ inner tie rods, Hotchkis springs rear end kit and tie rod sleeves, KYB shocks & struts, Kenny Brown SFC's, and Baer's SS brake system w/all braided lines. The car seems to be ready for the extra power now so I want to do it right. Something tells me things are aboout to get very interesting =).

 

Sounds like you have the start of a good plan. I think you will be pleased with the zz4 engine. I installed one years ago and like it. Like a before-mentioned post, I installed an accel lower manifold as the engine went in. Have yet to add the runners or the ported plenum. But that can be done easily in a weekend. If you go for the zz4, you must not use the supplied waterpump as it us for a v-belt drive.

 

Oh, one more thing. The ZZ4 heads are the same as the Corvette L98 heads, and they use the 85-86 style bolt pattern. You will need either an 85-86 style TPI intake, or an aftermarket intake to bolt it up properly. I found out the hard way, and had to silicone the holes to prevent leaks on my stock intake. I have a TPIS base that will go in shortly.

 

The cam change I was referring to would be something like a LT4 HOT cam, something very streetable but a nice noticeable increase in HP. Ported corvette heads will also give you a big boost in HP and torque. But seriously, you will need to port the intake or go aftermarket. Porting would be the most efficient way to do this and can be done yourself. Aftermarket can get VERY expensive.

 

I've been running one for over a year. If you have any questions feel free to e-mail me. I have an Edlebrock HI-flow intake. I did have a ported stock intake and there was a huge difference when I added the Edlebrock. I also smoothed out the Edlebrock. I am runnin ported SLP Semi-siamesed runners, ported plenum and unfortunately stock exhaust manifolds. I have the SLP 1 5/8 I just need to get em coated. I even have the y-pipe. Just funds are tight. Let me know.

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Rob P
89RSconvtZZ4TPI
92Z28convt5spd
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Thaks guys, I really appreciate the info. There are always unexpected things that come up with these mods, this board and the people on it have been priceless for turning those unexpected things into not such a big deal. The intake I have is from an '89, so I guess the bolt pattern is going to have to be dealt with. As far as the porting goes, this car will be driven most of the time to work and such and not "raced". I don't know if going to the trouble of doing the port work will be that noticeable to me. I have never run a TPI car before so i have nothing to compare it to. I know that the change from the TBI 305 to the TPI ZZ4 will be a drastic one as far as power goes, I just didn't know if it would make enough difference to make it worthwhile. I am looking more for the SOTP difference than anything, since the high rpm WOT performance probably won't come into play all that often. The car is geared tall (3.23 rear) and turns pretty slow at hwy speeds, but the T56 gives the flexability to wring it out at will. Let me know what you think. Thanks again, Rob.

 

Well porting the TPI (you can do this yourself on a weekend) will give you more bottom end torque and better gas mileage. Also it'll keep your motor pulling till at least 5000 RPM. It is definately a SOTP mod, when the ZZ4 is involved.

 

A couple posts mentioned changing the cam and possibly doing head work. If you decide to go that route, consider a less expensive crate engine. That's what I did when I changed mine over. The heads and cam were different and mine didn't come with the extras (h2o pump, intake, etc), but the inards were the same. This was fine because I wanted my own cam, had the TPI, and TW heads. Just another option for you.

 

Got my firesuit on here ...

If you are going THAT deep into the changeover, I'd skip the TPI and go right to the new RamJet.

The intake pulls more air right out of the box than the TPI, and is pretty simple to set up, as long as you have 12V power and fuel.

It sits a pretty as a picture in a thirdgen (they had one installed in a wicked Z28 at the woodward cruise.)

Best part is you get the Vortec heads and a roller stick. Plus, without telling tales outta school, there's another 75-100 easy HP in there (notice I did not say cheap)with the LT4 HOT cam and the Fastburn alloy heads.

The engine controller is a pretty simple, rugged marine based rig. As several people have posted, it's hard to HACK, but if you just want to screw it in and run like a bitch, this is a good place to start.

I'm told, but haven't seen, that all the sensors on the engine are production, and in pretty much the stock locations, so if you were to say, buy the ZZ4 Long Block, Fastburn heads and Ramjet manifold + air meter, along with a SD harness, and engine computer, that will work pretty well, too.

Only problems: EGR (no provision for this in any of the Ramjets) VATS (not sure if it still works or not in the conversion)

Might rock your world a little getting it in place, but it is definiely the stuff.

If the Guy from GMPP is out there looking down his imperious 2nd-Gen loving nose, or Johnny Hunkins the Last Thirdgen Magazine guy standing, they can take it from here.

Good Luck

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Bob
'87 Formula TPI 5-speed

 

I just read a post on this subject yesterday on this board - scroll on down to the topic of "what all tools do I need..." and read the 3rd post by steve91z28l98... Supposedly, you can bolt right up... Good luck... hth

 

[QUOTE]Rod, I am doing the same mods as you are doing.ZZ4 and 6-speed are on the shop floor. I have been trying to pull all the info together on parts and direction. I have a comp. cam 8-302-8[ not installed] a SD tpi.
All going into a 91 Z, Let me know how it works out.

 

Here's my little schpiel on what I woulda done if I'd have known better before I built my 355 for the chicken. Then again, all the stuff isn't yet available but here goes.

ZZ4 shortblock (no cam) -$1850 from SD.
Fastburn heads $1100 or so from SD.
Vortec/TPI intake (avail. in dec.) from SD.

Add your own choice of cams... too many good choices available.


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'89 Formula - Thunderchicken - 355 Vette L98/T-5/3.45 9-bolt/black/t-tops - the fun car!
'90 GTA - The GTA - 5.0 LB9/TH700/3.27 9-bolt/black/t-tops/tan leather - the cruiser.

 

Here's an update on the zz4 short block situation folks.. I have been in pursuit of one for a month or so now. The only dealer I have found in the ENTIRE country is one in Colorado that has the short block IN STOCK. He wants 2050 for it (about 300$ more then S.D.P.C). Not to mention around 200 shipped if you're out of range. G.M. says "sorry we just don't know" when they are asked when it will be available. So, if you know where to find one shipped for under 2000 GET IT... Oh yeah, and let me know too!