TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I thought the people of this board came to the idea that you couldn't run a 400 with the stock tpi this (http://www.gmhightechperformance.com...mhtp_warriors/) articles say "A .030-over 400 that was originally meant for his 1980 Camaro street car provides the thrust. Once the boys at Custom Design Performance in Columbia, Conn. were done with the short-block, Rob bolted up a stock TPI unit, which sits atop the 406 and breathes for aluminum Trick Flow heads. Thanks to the torquey mill under the Harwood hood, this Z has run 12.7s in the quarter with the factory chip still in the ECM."
I thought someone said that you couldn't run a 400 with stock tpi??
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My 87 Monte Carlo SS is running the same as you mentioned. I built a 406 with Trick Flow Twisted Wedge heads, flatop pistons, roller cam and a TPI off of a 1989 Fbody I converted to Speed Density. I am stock on the TPI other than some mild porting. I couldn't use the 350 injectors due to bogging, I installed 30lb units and it runs great. I shift at about 5400 RPMs and with a torque monster like this that is enough!! With my 3:73 gears and T-56 6-speed it's a blast!! Sure I could go with a mini-ram and make more hp in a higher RPM range but I drive it on the street and torque is what I want for the daily drive.
Not to disagree with anyone but most people that says 406's and stock-style TPI's don't work have never owned one.
Even with my heavy 36 lb CenterForce flywheel my 406 revs quickly and I have my rev limiter set for 5700 RPM.
That's exactly the combo that I want to build. I was going to use the Eldelbrock L98 corvette heads though. I belive their flow is 175 cfm for the intake.
Originally posted by wulff .......Not to disagree with anyone but most people that says 406's and stock-style TPI's don't work have never owned one.
Even with my heavy 36 lb CenterForce flywheel my 406 revs quickly and I have my rev limiter set for 5700 RPM.
Your engine will run, that's agreed. Shifting at 5700 rpm isn't your best option. You are way past peak and are loosing time. Get byour combo dynoed and you will see what everyone is talking about.
I had a 383 and stock TPI, the engine was begging for more air but the TPI couldn't feed it. I then converted to LT1 intake and WOW, big improvement. I gained 6 mph at the track (1/4) with only the intake swap.
Sure it can be done and will be a decent motor, its just that so much more could be had with a better breathing intake. It just seems like kind of a waste. Unless of course if it is heavily modded but this thread is about a stock tpi unit.
Yes, you can mate the T56 to your 350 (what year is your blocks?) I had to use a Centerforce flywheel as I was using a pre-one piece oil seal but as for the bolts it will bolt right up. My block is a 400 out of my original 78 Chevy 3/4 ton 4X4. I used a smaller starter out of a 93 Fbody.
As for me shifting way past my peak, my 406 is still pulling well past 4000 rpm... you have to remember, I built a torque motor for the street and that is exactly what I got. Not every car has to be built for 1/4 mi pounding. Bottom line is you have to decide what you want the car for and build the RPM and power range for just that, with my gearing and the 6-speed my RPMs on the street is great for my 406 TPI.
Also, the 383 is a higher winding motor than the 406 and if you build 2 identical motors (other than the cubes) you will find the 383 having to climb a lot higher to make the same horsepower and torque.
I talked to one of the techs at AZ TPI SPecialties and he said that there is a lot of info floating around about the 'stock' TPI and larger cube motors that just isn't right and said he would put my SS on the dyno when I am finished to see what I am putting out. I will post the numbers here when I get them.
A friend of mine put in a Edlebrock manifold and LARGE runners and said on his 350 he didn't gain much but did lose a lot of low rpm torque.
If you guys (wanting to install a T56 in your cars) have any questions I'll be happy to help, I took a lot of photos and aquired a bunch of info. I really love the 6-speed with my 3:73 gears I can cruise at about 1600 RPM at highway speeds yet have all the grunt I need in the lower gears.
Hey Jake, what kinds of mods did you do? I ported my intake out a lot and took off the EGR "wall" in the plenum plus I smoothed out everything I could in the flow stopping short of taking off the area between the tubes.
Originally posted by wulff
Hey Jake, what kinds of mods did you do? I ported my intake out a lot and took off the EGR "wall" in the plenum plus I smoothed out everything I could in the flow stopping short of taking off the area between the tubes.
Well, I went as far as I could.
Beginning with the plenum, I removed the obstruction just behind where the TB bolts. I opened the areas where the runners bolt, leaving just enough metal to allow for a good seal.
I'm using siamesed runners and I removed the dividing walls as far in as I could reach with my reciprocating blade. I attacked the dividing walls from both ends of the runners.
After cutting out as much of the walls as I could with the saw, I used a Mikita high-speed grinder reached in as far as I could to grind away all the burrs.
I did much the same thing with the intake manifold (base). I removed the diving walls as far in as I could reach and opened up the entries just as I did with the plenum.
I attached the gaskets (using bolts, washers and nuts to hold them in place) to the plenum and intake and used my grinder to open the gasket openings to match the plenum/intake.
If I recall correctly, I ended up with about 3-1/2" of wall remaining in the intake. I wrote down all the measurements I ended up with but I can't lay my hands on them right now.
Basically what I wanted to achieve was to allow each intake port more than one runner to draw from.
There are still a couple of inches of wall remaining in my runners that I couldn't reach. One guy on the Corvette Forum did the same thing, but went a step further and cut the runners open to be able to get at the remaining walls. He removed them then had the runners welded back up.
