In the never ending quest to get extend the HP curve a few hundred more RPM would switching from big tube AS&M runners to heavily ported siamesed SLP's make much of a difference? ( 355, xfi 268 cam, ported edelbrock base, trick flow 175's, long tube headers, no smog equip) Seems like all most of the folks getting the TPI's to pull up to 5200 to 5500 rpm are using ported siamesed SLP's. Thoughts?

 

Search for threads and posts by 1989GTATransAm. He took an SLP equipped TPI to 420whp. The SLPs will disappoint you when you first pull them from the box. The as cast runners are tiny and must be ported in order to make much of them. The best method I have seen involves cutting the casting open to gain access to the entire runner for porting. The runners get siamesed all the way down to just before they join the base. To make these really work you need at least a well ported ACCEL Superram, or other aftermarket big port base.

I personally went with the TPIS, or in other words, the AS&M, large tube runners with an ACCEL SR base, ported about as far as it can go without welding and a factory plenum ported the same way. With my twisted wedge heads and 290/290 .560/.560 112lsa cam, 1 3/4 headers, I shift at 6,300rpm and can bury the tach easily. I hit my 6,900rpm soft rev real quick shifting from 2nd to 3rd.

The thing with all of this is that you can spend less money and get more performance with either an HSR or Miniram. Of these two, I prefer the HSR, or in other words, the Weiand stealth ram. I spent $340+ on the ACCEL base and $420 on the runners. The HSR runs about $300 complete, rails and adapter fittings will run another $300 and you end up with more power and some extra cash on hand. The one downside to the HSR is its height. It barely clears the hood on the Camaro and doesn't allow for a strut tower brace. I'm working on a design to fix this for when I install the HSR on my car in the next year or two.

 

Roger that ASE

Unless youre willing to start cutting welding and make a science project out of it ($$$) get another intake manifold altogether thats up for the task as cast.

 

Yes, I know, a HSR would be a cheap route and would probably be good for an immediate 50+ rwhp with my setup. While not economical its more interesting to find ways to squeeze every bit possible out of TPI. I guess if I want to run with the new mustangs and camaros TPI has to go :-(

 

Talk to Dyno Don, his west coast crew has the quickest TPI cars around.

 

Siamesed runner will help extend the rpm range

 

I like messing with TPIs but honestly that what you just said is the smartest money spent. You can spend a ton of time and money on a TPI "just seeing" but that will get old quick. Results are almost all very close, noones going to unlock the secrets of the universe by porting differently. Don and a few others have taken that one imo to the limit

See it all the time-most wind up selling the setup and going to someting different..... go grab that extra power now and bolt it on now and move on to the next part of your project. The wheel is still round lol

 

Yep, the only reason I went back to tpi was for the appearence. Luckily I got a great deal on some SLP runners, though I would rather have the more stock looking AS&M ones.

The Stealth ram is the way to go really.

 

I ordered AS&M runners in October and still don't have them. You really might not have that choice.

 

Does TPIS still offer their large tube runners? Ive always had good luck dealing with them. Since I just mentioned them I remember one more little issue with the large runners. You need to use the large tube runner gaskets that are only available from the same people that offer the runners. I paid something like $40 for a set of these last year when I had my intake off. Should probably stock up on them in case they quit offering them.

I hope to be ready to move on my new intake next year. Then I'll most likely have my set up for sale.

I'll probably go with the stealth ram but with modifications. I will shorten the overall height to allow room for a strut tower brace. I'll also port it and convert it into an air gap design. I could also go with the mini ram but I just don't like the design that much.

The issue I have with siamesing the TPI is that it's not really TPI. I have nothing but the greatest respect for guys like Dyno Don and his people in Cali who take TPI to the max but, as they themselves proved on the super sized runner TPI project(2" runners), the long tubes just don't support high rpm. Since the small block needs to turn high rpm to make big power, this limitation makes TPI, in it's pure form, unsuitable for high HP applications. This doesn't mean that TPI can't work in a beasty street machine. My IROC Beasty is a very fast car and a blast to drive. The long runners give it a torque boost that makes it very streetable and when I hit the go pedal it moves right now. Hit it hard from a stop and it makes lots of tire smoke. Please don't tell my wife that last part. She wouldn't be too happy to hear about me smoking my brand new BFG Comp TAs.

As far as running with the new Mustangs and Camaros, the Beasty as it is doesn't give them much room to breath.

 

Actually, MR Gasket offers oversided gaskets, for about $25.

Part number 146

 

That makes sense. MR Gasket and ACCEL are both Prestolite companies. Accel would offer the gaskets for their Superram base and Street Ram large tube runners. I'll have to remember that if I need to pull my intake again for any reason.

 

Yeah, the repackeaged accel versions are about twice as expensive too.

 

Looks like I'm going to want a set of those gaskets pretty soon. I activated virtual dash on my ACCEL DFI gen 6 yesterday and saw IAT at -4 degrees. The ECM was adding 3.6% fuel to copmpensate for freezing cold air. Trouble is that actual air temp was a balmy 60 degrees. Definitely time for me to do the IAT sensor relocate upgrade and install an actual IAT sensor(not a coolant temp sensor) in the air filter lid. Then I can dial in my IAT correction table and correct my base fuel map which I spent many hours tuning last summer. Probably tuned around an added 3.6% fuel from a faulty manifold air temp sensor. Damn!