Jonathan Dyer

iTrader: (5)

I'm considering going EFI over the winter and wondering which way to go. There's lots of posts about the stock TPI setup running out of breath at 4500 rpm or so. I'm just wondering if the Hi Flow TPI base from Edelbrock (pn 3817) will support rpm to 5500 as advertised?

I'm considering this as opposed to an HSR because I already have the matching Hi flow runners and a TPI plenum. But they're not worth enough to be willing to make a major compromise.

So My question is would a "High Flow" TPI represent a real compromise vs the HSR?

My engine is a 383 with Vortec aluminum heads,509/528 lift, 222/230 duration on 112 LSA.

While I would love to get to the track once in a while, this car so far has been strictly street driven.

Thanks,
Jon

Orr89RocZ

iTrader: (20)

The vortec TPI base is suppose to be the worst TPI base out there with regards to flow due to port shape/size. They can be ported out to flow pretty well but takes time, money, and lots of work... just like anything else. I like the HSR for a 383...will support your goals of 5500-6000 rpm where that cam will run best. To get TPI up that high, you'd have to really open up the base manifold and slightly siamese the runners abit to extend shift point to 6000 rpm as that cam should be peaking in the mid 5000 rpm range.

If done right I dont think the TPI would give up much over the HSR but it will take alot of porting work to get the vortec base to flow as well as a box stock HSR. HSR's 6-7" runners are a better match for 5500-6500 rpm operations, so you'd have to siamese the TPI runners to shorten the length to push the same rpms. The california guys on this site seem to be the leaders in this mod..they have some impressive TPI setups that pull to 6000 rpm+... Really ported, really siamesed runner setups so they arent really TPI..they just look like one from the outside.

1989GTATransAm

iTrader: (3)

Orr is correct. If you have the Vortec base you are probably better off with the HSR. We have a porter locally who has squeezed over 320cfm out of the standard Edelbrock base. The price for that is $500. Then you have to have the runners opened up to match. I don't recall the price for that. All told it will probably cost you around $1000 to really open up a TPI system that will support say up to 600hp. Once the guy gets in there and starts cutting away the ports you might as well do the whole shebang for the little price difference.

The main reason we were doing it is to pass California Smog. However in the process we have learned how to really make some good TPI power. The HSR will be the easier route for most to go unless they like the looks of the TPI.

Guest

Its going to take a lot of work (or more likely, $) to get the TPI to flow. The HSR is probably going to serve you a lot better, out of the box.

vetteoz

iTrader: (13)

Compare the output graphs ( not the Hp #'s)

http://xtremecarzone.com.au/index.php?showtopic=386

Rod Behring

You would be leaving a lot on the table by using TPI, especially with a 383. My vote is for the HSR. The price for the base is almost the same as the HSR anyway.

Jonathan Dyer

iTrader: (5)

Thanks everyone for your informed advice.
Jon