robertfrank

iTrader: (27)

So I had an idea just shooting through my head and I wanted to get some input from you guys. I have been just tossing around the idea of just tearing apart my L98 car's top end and porting the hell out of it. (I own my own porting business). I was thinking about using Mr. Gasket 146 for the upper plenum and base, Fel-pro 1204 (1205 is honestly too damn big for my liking)for the bottom of the intake and for the heads. I also have a set of SLP runners that I'm now porting.MAYBE open up the heads to 2.00/1.55 LT4 valves. I already have a ZZ4 cam from my old 305 TBI I had so I'm good there. I can get a set of 24lb injectors for pretty cheap as well. For the tranny side I'm thinking about just getting an s10 converter for the 2200-2400 stall and I already have a transgo shift kit sitting on a shelf along with a brand new set of Richmond 3.42 gears. So I think outside of tuning I'll could be into it maybe $500-800 bucks at the maximum. So my question is is how well do you guys think it will run? I'd be happy with about 350 crank horsepower from it if it's possible, if not I've got no problem doing something else lol. I don't want to go to crazy as this car is my daily driver but I definitely want more power out of it.

Dakota W.

What are you doing as far as valvetrain? roller rockers? tappet? 1.5?1.6?

robertfrank

iTrader: (27)

I figure I'll just stick with the stock 1.5 rockers so I could run the extra set of ZZ4 valve springs I have. It's a 91 so its a roller motor to begin with. I also have an extra set of LS7 lifters I could toss in but I might just clean and reuse the stockers.

Dakota W.

The LB9 I had, had tappet rockers, not roller rockers. Roller motor refers to the lifters. 1.5 rockers will make it harder for you to get to that 350hp goal, I would go with 1.6 rockers because they give more lift than the 1.5s. you'll need different length pushrods as well if you go with 1.6 rockers. I got my roller rockers and 3/8 pushrods for around 350 bucks. I bought the rods from summit at summit for $115 for a pack of 8, so $230 for the rods, and the roller rockers off ebay for $130. If you're going to be porting and polishing, it makes sense to me to take advantage of that extra air flow.

robertfrank

iTrader: (27)

Well I don't want to go past the stock lift of .474 for the intake and .510 on the exhaust. If I were to run 1.6's on the exhaust it would put me at .544 lift which would require me to go with a bigger spring as the ZZ4 springs are only good for a .525 lift. I have a set of 1.6 comp rockers but they are being used for my 383.

Dakota W.

If you don't make your hp goal, I would suggest bigger rockers, since it's easier than tearing the engine apart and doing a cam.

robertfrank

iTrader: (27)

Well the plan IS to tear the top end off, port it and put in the ZZ4 cam lol.

Dakota W.

I know, I meant that you wouldn't have to do it twice if you just wanted to change the rockers.

robertfrank

iTrader: (27)

True true lol, I think 350 Crank hp would be fairly simple with this build if I were to go through with it. Truthfully it's in the hypothetical stages at this moment. If I can find me another set of Older LT1 heads I would like to modify them for SBC use and run either a Stealth ram or a modded single plane set up. It really depends on what happens after my other car is done.

robertfrank

iTrader: (27)

So anybody else have any thoughts on a build like this?

ASE doc

I assume you plan on replacing the stock manifolds with headers. I don't see making 350hp through the stock castings.

robertfrank

iTrader: (27)

The car already has 2460's and a full 3 inch Aerochamber exhaust. I was figuring 350 AT THE CRANK with this possibly.

ASE doc

I can see 350 from the combo. Port flow on the iron heads is one hurdle but you seem to have that handled. Port flow on the OE base is another issue. Ive hogged them out pretty big but the walls get thin real fast. The siamesed SLPs will help by shortening the total runner length to increase rev ceiling.

92droptopws6

iTrader: (10)

I can tell you from experience, what you want and what that motor is willing to do is two different things.. I have done MANY ZZ4 engines since 1989 the cam is sweet but takes full advantage of 1.6 rockers DON'T SKIMP here new valve springs are not too expensive not only that the ZZ4 GM ORANGE spring may be rated at the correct lift value for that cam aswell as the Lt4 hot cam BUT they do NOT do a Good job at valve Control at high rpm and that is EXACTLY where you need to be to make power.
What you are looking for is a minimum of 1 HP per CI and with that you have good valve lift that puts you in the 540-600 lift range on a 350 along with 10.5 being the minimum compression needed....
The killer of your entire combo is the TPI base manifold, you really need an aftermarket unit and fully port it or use a mini ram, Lt1 intake, HSR or Superram to have adequate flow...... The motor will make a TON of Torque but fall short on HP which comes on in the upper RPM.
Solid 350-355" shortblock
zz4 cam w/ 1.6(7/16) roller rockers non self alighning
L98 aluminum heads 2.00 1.56 valves, fully ported, comp cams 987 spring kit
Chromoly pushrods 7.200
Flat guide plates
7/16 ARP screw in studs( much better at deflection than 3/8)
HSR, or any intake set up besides the TPI will make your goal easy with proper tune, injectors etc.....

Dakota W.

The only thing I have to disagree on is the pushrod length. Get a checker, 15 bucks from comp cams. I'd rather pay 15 bucks instead of paying for new valves.

jamon8

iTrader: (3)

dude just put you stuff together with what you have. all ported out you will make 325-350 ponies and around 400 ftlbs of torque if you know what you are doing and make it all flow really well.

Dakota W.

There's more to making power than just air flow.

MassD

iTrader: (1)

This always seems to happen on these forums, someone comes up with a question about making some power on the cheap and before you know it they are buying heads and new springs yada yada yada. Take what you have put it in and run it. If you only make 330 hp or something like that who cares, you used parts you had saved money and made more power. Plenty of motors have been thrown together with extra parts and make plenty of power. With that cam and well ported head intake combo that isnt too large with some nice port velocity will probably peak around 5000 and make around 330 hp. And thats a nice little street motor than will be plenty reliable for everyday use. Take pics of the port job you do im curious!

Dakota W.

See, we're telling him not to just throw things together because his goal was more than 330 hp. If you bothered to read anything you would know this.

MassD

iTrader: (1)

I did fully read his comment, he is shooting for 350, did he say he wont settle for anything less? Is 20hp worth an extra 500-1000 dollars? Is he going to use that 20hp extra on a every day basis? Im sure he would be perfectly satisfied with 330-340 hp and not spend a single dime on anything else.

Dakota W.

I'm assuming he wanted 350 at the wheels, which would be more like 400 crank horsepower, which would be worth the extra 500-1000. Porting doesn't mean a whole lot unless you can use the extra air. It's not about using it EVERY day in a street car, it's about being able to use it when you need to.

robertfrank

iTrader: (27)

Actually I would be happy with just 350 CRANK horsepower. Should be more than enough for any daily driven street car. So let's not make this a big pissing match lol