Brisk

iTrader: (25)

I'm looking at starting to mod the '91 Z28 I've got.. and I'm curious about picking the right/good cam for this car. My goal is to have a fun TPI street driven car which can easily lay rubber and be a quick stop light dragger. Unfortunatly it'll probably never see a 1/4 mile track. Help me pick a good head/cam combo;

I've picked up Hooker Long Tube 2210's for it and I'll have a custom Y pipe, 3" I pipe, and Magnaflow muffler installed. I'm also in the process of picking up a Probuilt Street/Strip 700R4 with a 2800 RPM Vigalante stall which I will put in the car when it arrives.

Currently the car has 3:23 gears but I'll probably swap them out for 3:73s as the car is being built.

I'm considering using the cam combo I used on my 305 IROC - LT4 hotcam kit with 1/6 rr and 58cc '113' aluminum vette heads. This should be a decent combo for a street car that my wife can drive...

...are there better options out there? bring your opinions, this is a 'long term' project that will come together in the next year, not something I'm in a rush to do over the next week. I'd love to freshen up the engine and poke it out to a 383.. but we'll start this simple.

Thanks for your time.

Orr89RocZ

iTrader: (20)

Upgrade the TPI to some big tube stuff or maybe a different intake? That be a nice place to start since getting air in is important and stock TPI does choke 350 motors

If you want to stay TPI i'd try something like the FIRST system or better yet, a fully ported aftermarket base with siamesed SLP runners

hotcam would complement the SLP siamesed setup very well and would be a cheaper alternative to buying a new cam hotcams can be had for cheap these days

As far as heads go, you cant beat the AFR 180's for mild to medium TPI setups. For somethign like a heavily siamesed setup looking for alot more hp, or the other intakes like miniram or stealth ram, i'd go 195 cc heads

There are other head choices out there that are alittle cheaper but MOST decent heads are now in the 1200-1300 dollar range, so AFR's at around 1450 or so are not a bad deal! you get great valvetrain components with great port designs that flow like crazy


For a big tube TPI setup, and good heads like AFR's you could try the XFI 268 cam from comp. like a modern aggressive version of the hotcam but is much more idle friendly. That seems to be a hot setup and does make good power. Should get you well over 300whp with a big tube setup or other intake setup and drive very nicely. That be a FUN street car


And with 2800 stall thats a great overall stall speed from bolt on L98s to heavily modded ones. 3.23's are great gears for a street car. 3.42's would be abit more fun, and 3.73's would be proper for more of a strip car looking for best ET's

Long Beach Z-28

iTrader: (1)

Hi BRISK, You can't go wrong with any of ORR89RocZ recommendations. Feel free to do a search on his screen name and look at ALL his other posts. This guy knows how to spec out a street or strip L98. All his advice is excellent and if followed to the letter, your car will flat scare you and still be a 100% daily driver ( and pass any SMOG sniffer test) AS LONG AS you can get a good custom tune! Good Luck with your project! Pat

ZZ28ZZ

TPI makes its power mainly in the mid rpms due to runner length. By abt 4800 it starting to choke (4500 rpms with 383) even with aftermarket LTRs. IMHO, a 2800 stall is too high for a LTR setup. If you wanna keep that TC, I'd be looking for an intake set-up with shorter runners (miniram, stealth ram, superram). A superram and AFR heads are a proven combo and is what I'm saving for now.

FearThisGTA

I dont get over here that often but imo, depending on your budget( speed cost,how much $$$ do you have?) anywho, in the beginning I started with the basics like the free mods, then the suspension and drivetrain and then the engine. As you can see in my sig itg seems to work pretty good. As far as cams if you wanna stay with the TPI setup I would do the ZZ4 cam and ltr's as well as a 52mm tb and adj fp reg and bump it to 46 with your timmin @ 12 deg intial.

Oh and if you keep the 3.23's and do tack it to the track( alot more fun than paying tikets), the 2200-2400 stall will work nicely.

So, thats what I would recommend. hth Good luck.

Burnout91

This will do the job. Lay rubber?....yeah, a little.
Daily driver?...it has to be. -Bill

86 IROC

iTrader: (3)

Any way you can post alarger pic of that graph or a link? It's so tiny I couldn't even read it.

Burnout91

The main points of the graph are 375rwtq @ 4250rpm (probably would have been more if the run could have started lower in the rpm range), 321rwhp @ 4750rpm. Best part is 300+rwhp from 4250rpm to 5550rpm. Still had 283hp @ 6000rpm. Had 2 bad plug wires on the day it was tuned / dyno'd. -Bill

Orr89RocZ

iTrader: (20)

thats a nice combo. XFI does well with SLP runner setups but should work great on LTR TPI as well.

Burnout91

Yes, it's basically a practical example of the recipe that Orr89RocZ laid out.By the way, my car is one of the weaker specimens in SoCal. I've got some work cut out for me. But, I think it fits the bill for what the OP is looking for. -Bill

86 IROC

iTrader: (3)

Do you have any track times for the car in that configuration?

Burnout91

No, not yet. But I'm sure you will see some impressive times posted when Kevin91Z, 1989GTATransAm and crew get back from the track today. I should have been there -Bill

Orr89RocZ

iTrader: (20)

If you follow their builds you can make massive powerlevels out of a heavily modded TPI setup all teh while keeping a driveable car and emissions legal

i'm talking 350whp+ thats capable of high 11's in a lighter car properly setup. In decent trim thats still lower 12's at probly 113-115mph

tpi user

cant wait to see kevins and transams times i hope all that work pays off

86 IROC

iTrader: (3)

Agreed, I'm curious to see myself. It's been a long time in the making.

86 IROC

iTrader: (3)

Did they make it to the track? I haven't seen any new threads yet.

mikesanto70

I'm interested in doing a similar set up on my 92 L98 Heritage, what dollar range are we talking about to do it, 400rwhp

Blackdog36

iTrader: (3)

Brisk, how much do you want to spend? Good advice on here so far. I see that you are going to have a strong transmission which is good. You should think about beefing rear end up some (aftermarket girdle, zexel torsion pin, etc). I think you would better off sticking with 3.23 gears. 700r has high first gear ratio and stock L98's move pretty well. Moving up in gear ration with extra torque output may make car a little more difficult to launch and run through the gears quicker.

I bought a FIRST unit and am very impressed with unit. It is huge compared to stock. I think that if you are looking into buying aftermarket TPI parts (SLP runners, big mouth base, etc.) that FIRST unit is a good deal since it is around same price and flows the best. Will be around $1,200 by the time you get unit, AFPR, hose, fittings, etc. Price is comparable to a full TPIS system or hone extruded units. If you don't want to get to crazy, big tube runners only may work.

Aren't the 113 vette heads same as stock z28's just aluminum instead of cast iron? I checked and looks like GMPP sells ZZ4 heads with some port work that flow well.
https://www.thirdgen.org/forums/tech...num-vette.html
AFR's are real nice but so are Trick Flow G2 and chevy vortec bow tie heads for less money. FIRST is available with Vortec bolt patter. Scoggin Dickey sells TPI base in vortec bolt pattern and also vortec heads with upgrade springs for more lift.

Will you be getting your cared tuned? Keep us updated, interested to see what you decide on.