Cascade Crew

Ryan S · Posted: Sat Oct 22, 2011 6:52 pm Post subject: Porting and Other Bolt Ons

Hi everyone,
I'm running a 1991 L98 with a dbl roller timing chain, AIR Delete, Hooker shortys, MSD Streetfire Coil and a Dynomax catback system. I'm looking for a little more HP up top. Has anybody on here done, or have experience with Porting and siamesing the tubes/upper and lower intake, and can give me advice? Or upgrading to SLP runners? Also, can anybody give me input on running 1.6 ratio RR's are they worth it to upgrade?
All advice is greatly appreciated!
Thank You,

Ryan_S

Dewey316 · Posted: Sat Oct 22, 2011 6:57 pm Post subject:

I would look to go stealthram or something else like that, unless you can get a smoking deal on TPI parts (read: free), or just want to do it to try it out.

The issue with TPI's RPM limitions is only partly flow, the lenght of the runners is not good for performance above 4k revvs, its the nature of the long runner design.

1.6 RR's, I honestly wouldn't bother with them by themselves, I would rather spend the money to stab a cam in it.

Ryan S · Posted: Sat Oct 22, 2011 7:00 pm Post subject:

My biggest biggest problem is my car is a '90 and I still need to pass a few more emissions tests, and the HSR doesn't support EGR, a cam would be good, I'd really like to upgrade my block to a 4 bolt main one before I make my engine perform better at a different RPM

QwkTrip · Posted: Sat Oct 22, 2011 8:21 pm Post subject:

There's nothing wrong with 2 bolt main for the majority of people. Spend your money where it counts instead and help the engine breath.

blue89 · Posted: Sat Oct 22, 2011 8:33 pm Post subject:

x2 on what dewey said.

I dont think there is any reason to go to a 4 bolt main unless you are spinning that thing rediculously fast or making stupid amounts of torque. Seems that the turbo small blocks on the turbo forums don't really care between 4 or 2 bolt unless your in the 800 hp range. Absolutely no facts backing this up, just the general opinion I've noticed.

aaron_sK · Posted: Sat Oct 22, 2011 11:24 pm Post subject:

Don't need EGR to pass emissions in Washington state, they do not test for NOx on older cars.

TPI is stupid, throw that crap in the woods. Razz

Can't bolt on a port job so the title of this topic makes no sense.

Alphius · Posted: Sun Oct 23, 2011 9:05 am Post subject:

Agreed. No visual here in WA and no cares about the NOx, so you're good to go with a Stealth Ram. My Subaru handily passes WA emissions with no cats and no EGR.

Start worrying about a 4-bolt when you are making over 5-600RWHP.

TPI even with a port job and different plenum, runners, base etc still isn't too happy above 4k, like Dewey said it's runner length that is your big issue and there's no way to fix that aside from throwing on a different intake.

As the owner of an HSR on a mild 350, I will say that it will not give up a ton of low-end torque, but it will be plenty happy to flow as much air as you need even in excess of 6k RPM. It's a great budget intake that gives you more bang-for-the-buck than any other.

If you're interested, I can probably dig up and post my dyno graph and I'm sure someone else here with a graph for a TPI 350 could post one up as well. Aaron might still have his from the IROC.

Twilightoptics · Posted: Sun Oct 23, 2011 9:51 am Post subject:

Sorry guys. 4 bolt or allayed is needed at the 350 rwhp level. The problem is crank flex because the caps can't keep it in place. You wear the main bearings out in about 20k miles. Been there done that. And there is no reason to go 4 bolt unless you get a forged crank to go with.

aaron_sK · Posted: Sun Oct 23, 2011 9:54 am Post subject:

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2320

Ryan S · Posted: Sun Oct 23, 2011 11:00 am Post subject:

Hahaha alright, I guess I'll just save up and with the HSR.
Thanks a lot for the input everyone it's really nice to know what mods are cost effective before I just go out and waste money on stupid TPI ones.

Twilightoptics · Posted: Sun Oct 23, 2011 11:04 am Post subject:

Even if you got the ACCEL base, AS&M runners and ported the plenum to match, the TPI still has a TUNED issue which is what dewey was talking about. It's TUNED by runner length and positioning that causes a clash above peak torque. The Larger setup moves that number up to about 5200rpm, but if you've got good heads and cam, you'll need closer to 6000rpm.

You absolutely cannot beat the low rpm TPI torque though. The HSR will suck you in your seat slowely as it builds more power, TPI pins you to the seat instantly.

DBL_TKE · Posted: Sun Oct 23, 2011 11:34 am Post subject:

Whatever happened to making the best use of what you got? I was hoping for some good insight with this thread because I can't stray away from the stock TPI setup but instead got a bunch of same old responses saying not to bother with it.

Quasi-Traction · Posted: Sun Oct 23, 2011 12:37 pm Post subject:

HSR or Stealth ram, some kind of stand alone tuning system you can tweak with values on (Holley Commander, megasquirt, etc..) are a good investment. you'll be a couple thousand into it, but the tune-ablilty will make it seem worth while.

Then you can think about internal engine mods, (cam, rocker arms, 4 bolt block, etc.) because you'll have a platform that can be edited for mods.

<--humble .02

Twilightoptics · Posted: Sun Oct 23, 2011 1:22 pm Post subject:

Stealthram with AFPR for about $600.

What's the cost of a $400 Base and $2-300 runners?

End of story.

TPI is excellent in stock form, or built for towing.

Not for performance or power. Period. Sorry guys, it's just the way it is. It's not what it was built or designed for. We all wonder why it wasn't implemented into trucks but the TBI was.... because TBI has more power potential than TPI.

QwkTrip · Posted: Sun Oct 23, 2011 1:34 pm Post subject:

Leejo2005 · Member Joined: 12 Jul 2009 Posts: 466 Location: Kennewick

Just get one of these and be done with it.

http://www.ebay.com/itm/ELECTRIC-TURBO-POWER-AIR-INTAKE-SUPERCHARGER-KIT-NEW-?cmd=ViewItem&hash=item3a69d5a589&item=250883712393&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr

Alphius · Posted: Sun Oct 23, 2011 4:51 pm Post subject:

Maybe one day I'll get a truck and stick a TPI on it for pulling torque. That sounds like a great idea, actually.

Dewey316 · Posted: Sun Oct 23, 2011 6:24 pm Post subject:

IROCDave · Posted: Fri Oct 28, 2011 7:18 pm Post subject:

Save your cash, buy a decent sent of after market heads, cam and intake.

If you were able to open up the intake, the stock cam would be the next obstacle. The next obstacle would be the heads.

If your after performance, all three need to be changed. Intake, cam, and heads. The exhaust also needs to attention.