TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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Originally posted by l98+t5 hey doc i see you have 5.85 rods why is this? also i was wondering if i could get pistons to keep all the same stroke and bores of the 396 but bring the compression down to about 8.5?
You can order a custom piston from JE to match your stroke, rod length and desired compresssion ratio. My SB 454 is running a 22cc dish top with 6.125" rods..
Originally posted by TPIJeep You can order a custom piston from JE to match your stroke, rod length and desired compresssion ratio. My SB 454 is running a 22cc dish top with 6.125" rods..
That's a long rod for a long stroke motor! What's your deck height and is the wrist pin hole in the oil-ring lands?
I think the crate motor from World Products uses a 6" rod but I don't know the deck height.
Anybody use the GM crank that is 3.8"? They made it so that they could offer a 383 without the overbore. Build a 350 block .060 over with the 3.8 stroke. That would be a 394 . Aren't I creative when my math works. [/b]
Have you checked the price on that crank? It's been awhile, but the darn thing is a little on the pricey side. Maybe GM gold-plated it. Aftermarket is much more reasonable.
Originally posted by Parrydise7 Have you checked the price on that crank? It's been awhile, but the darn thing is a little on the pricey side. Maybe GM gold-plated it. Aftermarket is much more reasonable.
Actually I haven't. But GM is known to overprice almost all of there stuff when sold seperatly. I think it's because they do small quantity builds like the ramjet. Look at the price of the ramjet manifold bare. I still like the idea of there being a crank with a 3.8" stroke for those looking to make a stroker with an odd displacement . A 388, or a 412 sbc, hehe.
Originally posted by JPrevost That's a long rod for a long stroke motor! What's your deck height and is the wrist pin hole in the oil-ring lands?
I think the crate motor from World Products uses a 6" rod but I don't know the deck height.
Its a 9.300 deck, I went with the tall deck to get the longer rod length, I want to say the compression heigth is about 1.1 I don't have the build sheet in front of me....
The bottom of the oil ring land is at the top of the wrist pin hole so it uses a oil ring support.
Originally posted by Rick KingYou can make the tpi work, but it will take money big injectors possible a 9th and 10 injector. U will have to hog out the system to the max I hope you know a machinest who can do some work like custom and expermintal with the top of the induction.
Yeah... this is pretty much what we did. After installing the 454 block, we went with 32lb injectors, bigger throttle body, and ported out everything to the max.
On the stock L98 chip, she idles surprisingly well... but falls flat (and I mean flat) on her face above 4000 RPM.
I'd love to go with a Stealth Ram system myself, but after what was just spent for this engine.... it looks like I'll be running the stock TPI system for a very looong time to come!
Originally posted by TPI-454 Yeah... this is pretty much what we did. After installing the 454 block, we went with 32lb injectors, bigger throttle body, and ported out everything to the max.
On the stock L98 chip, she idles surprisingly well... but falls flat (and I mean flat) on her face above 4000 RPM.
I'd love to go with a Stealth Ram system myself, but after what was just spent for this engine.... it looks like I'll be running the stock TPI system for a very looong time to come!
The stealthram isn't very expensive if all you're going to do is replace the TPI. It reuses the fuel rail and everything .
Hey TPI 454 just a little heads up for you, I don't know how much more radical your setup is over mind but my 32lb injectors get to 98% duty cycle at about 5700 at 45 psi. I dynoed 511 hp and 568 ft lbs.
Originally posted by TPIJeep Hey TPI 454 just a little heads up for you, I don't know how much more radical your setup is over mind but my 32lb injectors get to 98% duty cycle at about 5700 at 45 psi. I dynoed 511 hp and 568 ft lbs.
Good Luck!
His cylinder filling will be a lot less with the TPI so his duty cycle will be lower than yours. He should be fine until he gets a stealthram or bigger intake parts.
When you add up half of the stroke PLUS the rod length PLUS the piston compression heigth, you should come up with 9.000". The stock deck heigth is 9.020", which means that at TDC, the top of the piston is 20 thou down in the hole. If the block is decked, then you will have something less than 20 thousands down in the hole by the amount that you deck the block. All right?
Half of my stroke is 1.9375" + 5.85" + 1.213" = 9.000" Any compression heigth less than 1.213" would put the wrist pin high in the piston and thru the oil ring grooves, not a good situation. So the 5.85" rods work well with the 1.213" compression heigth.
If you want a lower compression ratio than I have (10.0:1) Then you should get the pistons that have 22cc dished out on the top. I have the 14cc dished pistons.
Going back to the top: you should always have the stroke/2 + rod length + compression height equal 9.000". If you check these values for stroker kits that are sold as an assembly, I think that you will find that they always add up to 9.000"....
. Aren't I creative when my math works. [/b]
. A 388, or a 412 sbc, hehe. 
