Blown Ls7
Thread Starter
On The Tree
Joined: Jul 2003
Posts: 122
Likes: 0
From: West Virginia
Blown Ls7 I need some help on an issue I'm having with the LS7 I have installed into my 2001 vette. Here is the problem I had a LS7 built by Texas Speed and Performance ( Specs on the car are as follows:
Eagle ls1 stroker crankshaft
Eagle Ls1 h beam connecting rod set with arp bolts
texas speed ls7 flat top pistion set 3.88cc valve relief for ls7 heads
cnc ported ls7 heads
ls1 camshaft 232/240 .609"/.623" 115 lsa
arp head bolts
cometic head gaskets .051"
Procharger f1
A and A 8 rib pulley system
60 lb motron injectors
Here is the issue, my car on the dyno is at 700 lb of torque at 3700rpms and running 10 psi of boost,I'm being told that the Compression is to high (about 11.1) for this application! And if I lower the boost it will not help me! Because it would make the motor use extra power to turn the blower!And also the motor will not last long running like this! Anyone have any Ideas? Or Help? Its stressing me out LOL!!!
Eagle ls1 stroker crankshaft
Eagle Ls1 h beam connecting rod set with arp bolts
texas speed ls7 flat top pistion set 3.88cc valve relief for ls7 heads
cnc ported ls7 heads
ls1 camshaft 232/240 .609"/.623" 115 lsa
arp head bolts
cometic head gaskets .051"
Procharger f1
A and A 8 rib pulley system
60 lb motron injectors
Here is the issue, my car on the dyno is at 700 lb of torque at 3700rpms and running 10 psi of boost,I'm being told that the Compression is to high (about 11.1) for this application! And if I lower the boost it will not help me! Because it would make the motor use extra power to turn the blower!And also the motor will not last long running like this! Anyone have any Ideas? Or Help? Its stressing me out LOL!!!
I'm no expert and I'm sure some people will chime in but your compression is WAY TOO HIGH for a blower motor (especially running 10 psi). When you had the motor built, did you think you would be using a supercharger and did you ever convey this to Texas Speed? If you plan on keeping the motor in one piece, I'd either ditch the blower or ditch those pistons. Again, I'm no expert but that's my $.02
On The Tree
Joined: Jun 2006
Posts: 139
Likes: 1
From: Kaleva, Michigan
For what it sounds like you are wanting to do, you need to get your compression below 10.0. Lots of guys run in the low nines and in 8 for compression when wanting high hp. But with your compression, detonation is going to be a serious issue and pump gas may not be a good idea. Like Deezl SS, I am no expert. An expert will chime in soon enough though. Hope this helps.
Teching In
Joined: Jan 2004
Posts: 43
Likes: 0
From: Indiana
Weigh the cost of rebuilding vs the cost of operation with a high grade octane (112,116, E85).
Depending on your power goals the cost of rebuilding may have the advantage because the operating tolerances/design of an FI car tend to a touch different. e.g. FI/Nitrous pistons usually carry a larger ring gap with more piston head area for swelling...
If you want to leave things well enough alone, I'd consider taking the car off pump fuel.
Depending on your power goals the cost of rebuilding may have the advantage because the operating tolerances/design of an FI car tend to a touch different. e.g. FI/Nitrous pistons usually carry a larger ring gap with more piston head area for swelling...
If you want to leave things well enough alone, I'd consider taking the car off pump fuel.
11:1 compression and 10psi on pump gas is sure to result in detonation. If your going to leave it how it stands (which i wouldnt) I would recommend getting a meth/alky injection kit asap. The smart thing to do would be to pick up some dished pistons to lower the compression and I would still recommend getting the meth/alky kit as a safety valve. I would be cautious driving the car the way it stands now though as you could put some serious hurting on that ls7.
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8 sec potential, 12 sec slip
iTrader: (50)
Joined: Apr 2002
Posts: 4,092
Likes: 2
From: Savannah, GA
ya, your CR is way too high. Its a good idea to get a meth kit anyways as a safety net, but its not gonna be a magical fix all solution for your application. You need 9.0~9.5 SCR for that beast...
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Thread Starter
On The Tree
Joined: Jul 2003
Posts: 122
Likes: 0
From: West Virginia
no its not a case of too much money, and not enough research, I have sent 2 years researching this! TSP knew that it was a going to be a blown motor I think the signals got crossed! An honest mistake. Now I need help fixing it!
800rwhp with 427ci and F1 will not be a problem 1st lower the compresstion
and I dont think 60lbs Injectors will handle that much power but I could be wrong.
you can get there with less than 15psi on pump gas with good tune.
and I dont think 60lbs Injectors will handle that much power but I could be wrong.
you can get there with less than 15psi on pump gas with good tune.
Hmm I would def contact TSP thern because no way should they have given you that setup if they knew it was going to be used with an F1 blower. As others have said you be best with a CR of around 9-9.5:1, which you could do by just swapping out the pistons with some dished ones. With the rest of your setup 800 rwhp can def be done on pump gas however meth/alky injection is again always a good safety measure when pushing 800+ rwhp.
