Compression
9 Second Club
iTrader: (10)
Joined: Apr 2009
Posts: 1,230
Likes: 3
From: Joliet,IL and Las Vegas 50/50
Could you explain more? Did the low compression leave HP on the table? Was it laggy because of the compression? With the 7875 turbonetics, I hope to get 600whp.
Keith at PCM forless told me all his turbo LT1 he builds he runs them at no lower 10:1 CR. I mean Im not trying to run 25lbs of boost. But I thought with a little higher CR and maybe 8lbs I figured that would be a nice medium for the car, since the bottom end is all forged.
Keith at PCM forless told me all his turbo LT1 he builds he runs them at no lower 10:1 CR. I mean Im not trying to run 25lbs of boost. But I thought with a little higher CR and maybe 8lbs I figured that would be a nice medium for the car, since the bottom end is all forged.
Never sacrifice quench on any engine unless you absolutely have to. Quench should be the last thing you give up. The "perfect" quench is 0.040".
Quench does a lot of things for your engine. One of the big things is help prevent detonation. With FI, detonation is a big concern anyway. By increasing the quench, you'll significantly increase detonation.
You'll also sacrifice efficiency, performance, and power. Why would you want to do that?
"The quench area is the flat part of the piston that would contact a similar flat area on the cylinder head if you had .000" assembled quench height. In a running engine, the .040" quench decreases to a close collision between the piston and cylinder head. The shock wave from the close collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. Take note, on the exhaust cycle, some cooling of the piston occurs due to the closeness of the water- cooled head."
http://www.beckracing.com/page05.htm
Google is your friend.
Quench does a lot of things for your engine. One of the big things is help prevent detonation. With FI, detonation is a big concern anyway. By increasing the quench, you'll significantly increase detonation.
You'll also sacrifice efficiency, performance, and power. Why would you want to do that?
"The quench area is the flat part of the piston that would contact a similar flat area on the cylinder head if you had .000" assembled quench height. In a running engine, the .040" quench decreases to a close collision between the piston and cylinder head. The shock wave from the close collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. Take note, on the exhaust cycle, some cooling of the piston occurs due to the closeness of the water- cooled head."
http://www.beckracing.com/page05.htm
Google is your friend.
Never sacrifice quench on any engine unless you absolutely have to. Quench should be the last thing you give up. The "perfect" quench is 0.040".
Quench does a lot of things for your engine. One of the big things is help prevent detonation. With FI, detonation is a big concern anyway. By increasing the quench, you'll significantly increase detonation.
Quench does a lot of things for your engine. One of the big things is help prevent detonation. With FI, detonation is a big concern anyway. By increasing the quench, you'll significantly increase detonation.
My question is to you now is, You dont think the loss in quench can be made back in running more boost?
Quench is generally considered less important in FI because of dished pistons. Depending on the dish that area affected by quench can be quite minimal if it's a huge dish. If it's smaller like a valve relief flat top then it becomes quite important.
No mine are 55CC. When they were advertised, they showed them as FI heads. I even called TFS and made sure of it. They have 23 degree valve angles on them.
I have 16CC dished on them
I have 16CC dished on them
Quench is the area around the chamber, where the top of the piston comes close to the flat cylinder head surface. During assembly, you want to get space down to 0.040", and no less. At 6,000 rpm's rods, pistons, and cranks tend to stretch a little, and aluminum dimensions change because of heat. That can bring your quench area down to nearly 0". You can guess what can happen if you start with a quench area of 0.020".
Back to the purpose. As those two flat surfaces rush towards each other, it pushes the air:fuel mixture towards the center of the actual chamber. It also creates a lot of turbulence, like a hurricane. That turbulence keeps the mixture very fine, for a more rapid burn. And the high pressure movement tends to cool off any hot spots.
All of that is intended to keep a fast burn inside the actual chamber where it's most efficient.
If you do a google search, you'll find reams of information on this stuff. I remember a while back some one was experimenting with drilling holes through the first ring land so some of that quench pressure pushed on the first ring and improved sealing, but only during the ignition event. IDK whatever came out of that.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
http://www.carcraft.com/techarticles...ng_technology/
The ultimate in ring seal is drilling the pistons for gas ports. Compression rings normally need about 0.002-0.004-inch (vertical) ring-to-groove side clearance to allow cylinder pressure to get behind the ring and force it to seal against the groove and cylinder wall. Gas ports apply combustion pressure directly to the back of the ring, allowing the virtual elimination of side clearance. Since the ring is restrained by the groove itself, there’s less opportunity for high-rpm ring flutter. Very thin, narrow, and lightweight 0.043-inch–thick rings are needed to reap gas-porting’s full benefits. Gas ports work best with short piston-compression heights (under 1.200 inches) on engines running 7,000 rpm or higher. The major drawback is that all this positive pressure greatly shortens ring life, so it's not recommended for street use.
That's the reason why I am asking questions about quench and FI not just quench alone.........because what im getting at is still having decent quench but not actually worried about being spot on with the recommended .040 of quench.
Essentially you are forcing more air into the chamber where as with a tighter quench and my CR you would have to worry more about pre-detonation correct?
That's all im asking.........
I run 8.8:1 CR in my boosted LT1. I am running 15#'s of boost (Procharged D1SC), 93 octane and meth injection and a large FMIC. My setup is overkill for safety and I know that.
With my lower CR, I don't find the car laggy, but I am sure with a higher CR it would help slightly. I have plenty of videos of my car if you want to see what it drives like and make your own opinion on if you think the 8.8:1 is too laggy.
What others have said is true. If you plan on running straight E85, I also think you'll probably be okay with your current CR. If it were me, I probably would drop the CR slightly just to give me a little more wiggle room to grow and piece of mind, but as long as you don't go pushing 20#'s of boost, you should be okay.
I don't think too highly of Kieth at PCM's for less ever since he left me high and dry after a bad tune (he literally took my money after the dyno tune and as the car wouldn't leave his parking lot without dying, he told me he couldn't do anything better for driveability and that I just needed to drill a hole in my TB), but to each his own opinion.
Hope this helps.
With my lower CR, I don't find the car laggy, but I am sure with a higher CR it would help slightly. I have plenty of videos of my car if you want to see what it drives like and make your own opinion on if you think the 8.8:1 is too laggy.
What others have said is true. If you plan on running straight E85, I also think you'll probably be okay with your current CR. If it were me, I probably would drop the CR slightly just to give me a little more wiggle room to grow and piece of mind, but as long as you don't go pushing 20#'s of boost, you should be okay.
I don't think too highly of Kieth at PCM's for less ever since he left me high and dry after a bad tune (he literally took my money after the dyno tune and as the car wouldn't leave his parking lot without dying, he told me he couldn't do anything better for driveability and that I just needed to drill a hole in my TB), but to each his own opinion.
Hope this helps.
I run 8.8:1 CR in my boosted LT1. I am running 15#'s of boost (Procharged D1SC), 93 octane and meth injection and a large FMIC. My setup is overkill for safety and I know that.
With my lower CR, I don't find the car laggy, but I am sure with a higher CR it would help slightly. I have plenty of videos of my car if you want to see what it drives like and make your own opinion on if you think the 8.8:1 is too laggy.
What others have said is true. If you plan on running straight E85, I also think you'll probably be okay with your current CR. If it were me, I probably would drop the CR slightly just to give me a little more wiggle room to grow and piece of mind, but as long as you don't go pushing 20#'s of boost, you should be okay.
I don't think too highly of Kieth at PCM's for less ever since he left me high and dry after a bad tune (he literally took my money after the dyno tune and as the car wouldn't leave his parking lot without dying, he told me he couldn't do anything better for driveability and that I just needed to drill a hole in my TB), but to each his own opinion.
Hope this helps.
With my lower CR, I don't find the car laggy, but I am sure with a higher CR it would help slightly. I have plenty of videos of my car if you want to see what it drives like and make your own opinion on if you think the 8.8:1 is too laggy.
What others have said is true. If you plan on running straight E85, I also think you'll probably be okay with your current CR. If it were me, I probably would drop the CR slightly just to give me a little more wiggle room to grow and piece of mind, but as long as you don't go pushing 20#'s of boost, you should be okay.
I don't think too highly of Kieth at PCM's for less ever since he left me high and dry after a bad tune (he literally took my money after the dyno tune and as the car wouldn't leave his parking lot without dying, he told me he couldn't do anything better for driveability and that I just needed to drill a hole in my TB), but to each his own opinion.
Hope this helps.
Plus I just dropped my CR from almost 10:7 to 10:5. I didn't go any lower for the sake of quench.
You have a link to your vids? Love to watch them
WOW!!!! Man im really sorry to hear that. He seemed to know his stuff when I talked to him. Hope he doesn't do me like that! Im running meth to save myself incase I decide to run 8+lbs of boost.
Plus I just dropped my CR from almost 10:7 to 10:5. I didn't go any lower for the sake of quench.
You have a link to your vids? Love to watch them
Plus I just dropped my CR from almost 10:7 to 10:5. I didn't go any lower for the sake of quench.
You have a link to your vids? Love to watch them
Here's a few of my vids. This first one is probably the best for example of acceleration from a dead stop. All of these were back when I was 614 RWHP. I'll get some new ones this year of its current 700 RWHP level.
http://www.streetfire.net/video/0-160-40_2417706.htm
http://www.streetfire.net/video/battle-of-the-z28s_187925.htm
Yeah, he talked a good talk over the phone and while he had my car on the dyno to me as well, but then as the car sputtered and died in his parking lot he offered basically no assistance. Bryan Herter of PCM's for less eventually made things right again, but it was clear that Keith was just interested in shooting the sh*t, and taking my money, and NOT about making things right.
Here's a few of my vids. This first one is probably the best for example of acceleration from a dead stop. All of these were back when I was 614 RWHP. I'll get some new ones this year of its current 700 RWHP level.
Here's a few of my vids. This first one is probably the best for example of acceleration from a dead stop. All of these were back when I was 614 RWHP. I'll get some new ones this year of its current 700 RWHP level.
It really depends on how much boost you plan on running, and what transmission is in the car (if you mentioned what type of tranny, I must have missed it).
If you are a 6 speed, and have around a 3.73 rear, and run 10#'s of boost, depending on your timing, you should be north of 600 RWHP I would think.
FWIW, the meth injection really isn't going to do much for you if you plan on running E85 full time. E85 will keep you farther away from detonation than say running meth injection with pump gas. If you get past the few shortfalls of running E85 (not everywhere sells it, you get worse mileage with it, and there are different blends you'll need to tune for, along with building the fuel system to support it), it really is superior, and adding meth to it will not be necissary .
If you are a 6 speed, and have around a 3.73 rear, and run 10#'s of boost, depending on your timing, you should be north of 600 RWHP I would think.
FWIW, the meth injection really isn't going to do much for you if you plan on running E85 full time. E85 will keep you farther away from detonation than say running meth injection with pump gas. If you get past the few shortfalls of running E85 (not everywhere sells it, you get worse mileage with it, and there are different blends you'll need to tune for, along with building the fuel system to support it), it really is superior, and adding meth to it will not be necissary .
I have a T56 with factory 3:42s. I plan on running 4-5lbs while driving to work and 10-15lbs on track days. I was just running meth to be on the safe side after 10lbs because of the CR. Not really trying to depend on meth
If you crank the boost up to 15 ish pounds, I bet you see around 700 at the wheels. This is my guess. I can garuntee it will be a very stout running street car
Again, the benefits of running the meth injection will be already had by running E85. To be honest, I don't know that running meth injection on top of E85 will give you any added benefit.
If you crank the boost up to 15 ish pounds, I bet you see around 700 at the wheels. This is my guess. I can garuntee it will be a very stout running street car
If you crank the boost up to 15 ish pounds, I bet you see around 700 at the wheels. This is my guess. I can garuntee it will be a very stout running street car
Ok. So you think I should hold off using the meth kit because the E85 is enough? I guess the meth is for running 20lbs+ of boost? People say its a band aid and I understand why. But I wasn't trying to use it as a band aid. Just as a safety valve for when I try to run high boost!
Nothing stopping you.