i have have a stock l98 in my 91 vette. slowly getting into the motor. already have every bolt on possible and just got done putting on my tpis long tubes. the next question is what intake to go with. should i get the ported base and runners. or the mini ram. ill problable keep the stock heads on it for another year and do the cam and heads at the same time. but right now i want to do the intake. id like some advise of people that have used both setups.

 

anyone?

 

Call TPIS and tell them your plans, they will point you straight.

 

i talked to tpis aready and they said it based on preference. i was just wanting opions of people that have used both.

 

TPIS is right, what you should get is based on your preference and what/how you want the car to run.

Personally, I kept the TPI, went with the base, large runners ported plenum, etc., etc., etc.

I wanted to keep all the torque and improve the power because thats where I spent most of the time with the car - lower in the rpms, cruzin around.

If you see yourself high in the rpm range a lot then this won't work for you.

 

Keep in mind that TPiS is only going to give you options that they sell. So you're never going to hear a word about the superram or the stealth ram from them.

Its up to you. Do you want a lower RPM stump pulling torque monster that makes good horsepower, a high RPM horsepower monster that makes good torque or possible a medium ground of both?

I'll tell you right now that if you go miniram I'd suggest doing a whole lot more than just the upper end.

 

I have done both. Initially I did the standard set of easy upgrades (52mm, MAF screens, true dual exhaust, gutted AIR pump, MSD, AFPR, balanced injectors, cold air induction with K&N, etc.) and then I ported my plenum and installed a Big Mouth manifold and large tube runners (I had trouble with the bolt holes lining up, by the way). The Big Mouth/runners definitely added noticable power, however, the engine stilled fell on its face at about 5,000 rpm. Currently, I have a legitimate 420 hp engine (at the flywheel). I pulled the engine to rebuild it, bored it out to 355, installed 10.25:1 KB pistons, ported and polished stock aluminum heads professionally and went with the big valves (2.05s) beehive springs and titanium retainers, added a ZZ9 cam (roller), 1.6 Comp full roller rockers, 24# FMS injectors, Bosch+4 plugs, and the MiniRam. The engine now spins to about 7,000 rpms and makes usable power up to about 6,600 rpm.

Personal preference is still the right answer so here is the bottom line: with the Big Mouth/runners you will have more torque down low (long runners make low rpm torque but breathing becomes an issue as rpm rises), and therefore your hp peak will be at a lower rpm - the downside is that you will definitely be limited as to how much hp you will make - probably by up to 60 hp based on my set-up (maybe even more). With the miniram/ZZ9 you have shorter runners (but longer than LT1) so the whole curve shifts up the rpm range - less torque down low, but higher rpm and therefore substantially more hp. And don't misunderstand the miniram/zz9 makes plenty of torque - just not down low.

Last point, if you do a miniram, change the cam or you are wasting your money. If you are absolutely staying with stock cam and un-ported small valve stock heads go with the Big Mouth/ runners

 

i am definately going to change the cam and at least port the heads and bigger valves, if not go with tpis afr's. but not at this point. so you think the mini ram with the stock cam wont work well for now? the other problem is the mini ram comes port mached for different size heads. if i buy a mini ram for my stock heads which use a #04 gasket i think the afr's use a #05 gasket.then they will not match. right?

 

Think about it. You're taking a cam that is profiled to make low end torque and peak power around 4200 and sticking an intake that makes less low end torque and peak power over 6000 on top of it.

 

Not sure what you mean by different "size" heads. I had my stock '88 heads ported, polished, and gasket match ported (they also had to do some bowl radiusing to use the big 2.05 valves). TPIS will send you the right gasket if you tell them what heads you are using. Just make sure you port the intake inlet of the head to the full size of the gasket. As an engineer myself, for the money, I think stock heads are very under-rated - even Lingenfelter spoke very highly of them in his book! You can save several hundred dollars by "working" stock heads instead of buying aftermarket, and you get a head that is more than 9/10s of the best aftermarket, no fitment issues, etc.

But the whole issue is irrelevant if you don't change that cam. In fact, IMHO a miniram setp-up with stock cam would probably run quite poorly!

 

i think your right.

 

Take a look at Vic'89's or Joe90's performance figures for an idea of what can be done with a modified TPI setup. Also there is data on my site with results of such mods to the L98 in a '90 Vette.

If you want to push the power band upward a little right now with only a little low end loss for almost no $$ just port the plenum, upper runners and siamese the stock base. You can see the results in dyno pulls on my site. Now my shift point is around 5,600rpm and with heads, cam & headers it is predicted to pull to a little over 6k RPM for best ETs.

You could also begin to think of some mods to your A4. If you want to keep most of the stock feel, go with a 2,000rpm TC (yours is a 1,500rpm) and TransGo shift kit. The former will allow you to launch a little higher into the power band while the latter will make heavy throttle shifts a lot more fun.

 

oh i forgot to tell you, i have 6 speed trans.

 

I've just been thru this and have learned a few things. I'm still just an idiot, but I do know a few facts here and there, I learn them literally day by day.

If I were you, I wouldn't even consider a miniram unless you plan on doing ALOT more, as was previously stated. You're going to need to carefully match a cam, the heads ("garage porting" as they say, down the local shop ain't gonna cut it, you're going to need excellent CNC'd heads, and this job is terribly expensive) with that upper breathing intake. But now you'll be spinning big RPMs, and your bottom end will need upgraded as well. Are you sure you want to do this on your L98?

Scorp asked the perfect question. To stay in "safe" RPM range (upper 5,000's to maybe 6,000 at most when you shift your 6 speed in 1rst two or three gears), go all-out and port your TPI or better yet get some aftermarket parts and have them preofessionally ported to all match as a system....a little more expesive yes, but better gains there. For the L98, I would go full Supperram intake and get those '91 heads fully ported with 3 angle vavle job, the works.
Get a cam like the LPE 219/219. With this setup, you'll have all the power from off-idle on thru to upper 5,000 RPMs that you'll ever want on a street machine, it will feel like a super-amplified L98 that you love. Miniram? Thats more like a super-powered LT1, if you want that. Again, the "system cost" is much higher if you do that miniram thing. LPE did an ungodly great job with SR/219 cam/upgraded heads setup, I've heard about this from too many people now who have done it and know what they're talking about. What you'll be doing is screeching down the street going sideways the whole time:lol:

And this is what I've learned, today and everyday :D

Good luck! :cheers: