What's up everyone, (also posted in ENGINE Turbo)
I'm in the middle of building a 4 bolt motor to replace my 2 bolt. I have 15G turbos, Pauter Rods, brand new oem crank, ARP head and main studs, Ross Pistons, Torque plated machine work, some head work, Aluminum flywheel, aluminum crank pully, AEM wideband, AVC-R, S-AFC, Walbro pump, and some other stuff......
Here's the question. The machine shop just received the pistons from Ross, but he got flat topped 9:1 ratio pistons. I was pretty upset when I saw that they weren't 8:1. I want to know if anyone has a 9:1 ratio in their VR-4,(saw one kid here, but it was a FWD TT conversion and he only has 9B's and everything fuel is stock) and if you ran into any tuning problems. I'm planning on running 15-18 psi with the 15G's and don't want to have to run race fuel all the time. Any past experiences welcome. Basicly, I want the most power on pump gas, and any extra I'll tune for with a race fuel map. I don't want to need race fuel for anything over 12psi...you know. Any and all help will be appreciated as I need to make an immediate decision if I plan on driving the car this spring.
Thanks in advance,
-Mike Vincent
91 VR-4 Rhode Island
Don't be concerned so much with the PSI you want to run, if your running higher compression you'll make more power with lower boost. However your potential may be limited.
Don't be concerned so much with the PSI you want to run, if your running higher compression you'll make more power with lower boost. However your potential may be limited.
He wants the "most" power out of pump gas not "good power"
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Brent - Great Depression Racing
1992 Duster 11.54@125 22psi BONE Stock 6g72 12 valve - 12.7@114 14psi boost -516whp 519ft/lb 20psi (Old 3.13L built shortblock) - Precision 6765, Tial 38mm open dump, 3" open downpipe, 20x12x3" evo style intercooler, Stock 10:1 diamante 12 valve shortblock with regapped rings. heavily ported heads (+40% on flowbench), Ferrea Competition Plus +2 +1 stainless valves, Nielson Vintage Racing 278 custom turbo cams, RPW cam gears, Custom Ram Style short runner intake manifold, 12 Gal Jaz Fuel Cell, Dual external Walbro GSL392 255HPs, Dual 5/16" feed lines, Trick Flow AFPR, 3 puck solid hub & 3300# DD plate, OBX Torsional Diff, Zeitronix wideband/EGT/Boost, 2100cc 3 nozzle DevilsOwn Meth. Running on 4.0 BAR Megasquirt II, 47# Inj, E70 Fuel
1994 Spirit - 13.987@101.89 - 5psi- 6g72 SOHC, K27 Turbo http://videos.streetfire.net/video/9...-on_649313.htm
z06 is a 11to1 engine and has a tt kit for it. they only run like 6psi. because that is all they really need. higher compression is more hp, so you go and add boost and now you have even more hp. must run high test gas, and watch closely for knock is the downside. you wont need as much boost is what im saying to make xxx amount of power.
More power with less boost and it shouldn't be as bad as the FWD's with their 10:1's.
Besides your all built up, and knock, although bad, shouldn't hurt the internals as much as it would a stock block :P
GL man, I'm chugging along with my rebuild! Thank Tony for me will yah, hes bring it down on the 29th :P
To a point. Higher overall compression increases the efficiency of combustion but ultimately you make more power from more air and fuel.
So a more correct statement would be more power with equal boost, but still if you have 8:1 and are running 18 psi with it, you will make more power than if you had a 9:1 running 15 or less.
That extra 3 psi forces that much more air/fuel into your combustion chamber. The most powerful setups are the ones that get away with the most boost and that isn't just this platform, thats all platforms. Whoever gets the most air/fuel in, can make the most power from said air/fuel.
One of those golden rules which most everything is based off: Energy can neither be created or destroyed, merely transfered.
The energy that ends up on a dyno or moves you down the road comes from COMBUSTION, in your internal combustion engine. You want more power is basically saying you need more energy, which means you need to complete more combustion by adding more air and fuel.
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Red 93 RT/tt project car
Mods: stillen dp, custom exhaust, Spec stage 2 clutch, RPS FW, 3sx lightweight crank pulley, BCP7RES-11 @ .030 gap, autometer gauges, dsm SMIC's, Tein S springs, pte 580 inj's, hotwired walbro, maximal performance solid motor mounts, DR plenum spacer.
z06 is a 11to1 engine and has a tt kit for it. they only run like 6psi. because that is all they really need. higher compression is more hp, so you go and add boost and now you have even more hp. must run high test gas, and watch closely for knock is the downside. you wont need as much boost is what im saying to make xxx amount of power.
APS, the company that made the turbo kit for my GTO also made one for the new Z06. Its true they made about 650rwhp on around 5psi, but the engine already made 450rwhp stock, and the heads are basically C5-R racing heads which are much better flowing heads then out 3S heads and the car would have made 800rwhp easily on pump gas had the compression been around 9:1. With our cars, with TD04s, if your running 8:1 your lucky to get 400awhp on pump gas but at 9:1 you will probably make that 400awhp on a little less boost but your going to have to be a little more careful tuning it.
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9:1 compression ratio VR-4 ??GOOD/BAD??
and was very happy.
