When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
This is a build we are doing for a good friends 2004 GTO with a T56, Monster Twin Disc Clutch, 3.46 gears. Shooting for the 450-500HP on Motor + a 200 shot.
LM-7 Block machined/bored to a 3.903
ATK Reground 3.622" Crank
Scat I Beams with ARP 8740 Bolts
Wiseco Flat Tops 10.5:1 Compression
Wiseco GFX Rings Gapped for Nitrous
#799 Heads Ported by our very own Matt Helms In. 301cfm / Ex. 203 @600
Stock Rockers with Trunion upgrade
Straub custom Hyd. Roller Cam .225/.231@ 50 .537/.517 110LS
Fast 102mm Intake/Throttle body/Fuel Rails
Powerbond 25% Underdriven SFI Balancer
The engine will be dyno'd with a carb setup at first and will report back with EFI and RWHP numbers when done. Should be a very nice Street/Strip Combo.
Last edited by ATK Engines; 12-17-2015 at 01:41 PM.
Just out of curiosity why such low lift numbers on the cam? If the heads are flowing a touch over 300 cfm at .600 lift why limit the motor to .540 lift.
Just out of curiosity why such low lift numbers on the cam? If the heads are flowing a touch over 300 cfm at .600 lift why limit the motor to .540 lift.
Cam was spec'ed out for the customers needs, not a max effort deal, but room to grow later on. He didn't want to sacrifice drive ability. He wanted peak RPM to be 6200-6500 RPM so Chris shortened everything to pump as much velocity into the cylinder to reach his goals with that and the NOS in mind.
Just waiting on pushrods and she will be ready for the dyno.
Just got it off they dyno, this was with the old Edelbrock Performer RPM Intake and a 750 double pumper. We would have liked to used a nice single plane, but this was just for a reference. We will be getting it in the car and adding the Fast LSX 102mm Intake and Throttle body with a good tune and see what she does. We made another pull to 6500 and she held on making peak power at 6300 RPM on that pull at 470HP.
That TQ curve is insane and is going to get this GTO moving!
That cam is awfully small, especially for shooting 200 to it. What was the correction factor for the engine dyno?
Chris said it best on the Chevelle forums:
Any head will reach a lift that 100% fill rate of the cylinder at the given rpm range is achieved. You want to past this by about 10%. After that anymore is a waste.
"Bigger is Better" is the marketing theme this industry is based on...I'd rather say the "Combo is King".
Since torque is what we measure I told Brandon and the owner that this little engine is going to surprise some people.
I'm puzzled why you're using a mild 347 as a build to highlight? ATK doesn't have a huge following here, so doing a build thread makes sense... but most folks wouldn't be buying a 347 nitrous motor. 370... 408 yes. Or a 347 turbo motor?
I'm puzzled why you're using a mild 347 as a build to highlight? ATK doesn't have a huge following here, so doing a build thread makes sense... but most folks wouldn't be buying a 347 nitrous motor. 370... 408 yes. Or a 347 turbo motor?
We have been doing alot of LS builds under the radar and can build them any which way. We just did not want to focus on them because we are so swamped and under staffed with our other product lines still being our main product lines. We have been working with Straub, Texas Speed and our own builds trying out different combinations going for the best bang for your buck. We plan to make 2016 our big year for LS Engines bringing them to the main stream at a very attractive price point with different power levels and quality parts.
There is a large market for this type of build. We get a lot of customers with LS1/LS6 engines looking to go to an LM7 based build to have a stronger foundation.There's a lot of people looking for that 450-500HP Range that dont want to pay the additional $ for an LQ4 based build since core costs have jumped and are very hard to get.
That's good to hear. I just know how things go around here and what tends to sell product. I don't discredit the idea of doing a budget build, but I would think you need to showcase what you can do at some point as well.
That's good to hear. I just know how things go around here and what tends to sell product. I don't discredit the idea of doing a budget build, but I would think you need to showcase what you can do at some point as well.
I definitely agree, believe me...I have been trying to focus on the LS line for sometime. We sell a lot, but a lot is private label so you would never know its our engine or short block being used.
She will be finished up tonight and than we just need the exhaust to get her on the the chassis dyno and do some tuning and get some RWHP numbers! Exhaust should be here by the weekend with any luck.
I actually love the combo. It shows what a stock ls1 shortblock can do with the same heads n cam setup on an actual engine dyno. Lots here also doing the 200 shot on a stock rotating assy. If I were to do another build it would probably be similar to this top end setup with a comparable size hit on the bottle. Thanks ATK for the info.
Thank you guys. We have an appointment for the 19th for the chassis dyno. He decided to order new Spintech exhaust and wants it on for the dyno.
We have a few other similar builds coming up that we will post the results on. A few LM7 383 versions with TSP ported heads, one like this with a cam that has more lift, few LS6 combos amongst other builds. We will be playing with cams as well getting a new line of LS engines together finally. Everything we do now is custom.
We had a bit of a delay. During the original chassis dyno session 2 injectors stuck on him. Had to order up some new injectors and wait to save up some $ for another tuning session....but we finally got it done last night. Ended up with Siemens Deka 42lb injectors.
Andy @ Prime Tuning here in DFW did the work on Keith @ Speedteks dyno jet, thanks to these guys!
She ended up making 386HP/380 TQ at the wheel, right at about a 15% loss. He is still breaking in the new clutch, but the TQ really puts it down on the street! With some seat time this weekend, hopefully the clutch will be broken in to really lay into her!
12-11-2015, 03:45 PM
ATK LM-7 5.7L Nitrous Build Up 
I will say, the TQ is amazing, she just keeps pulling! 
