Stage7

iTrader: (1)

It's taken 9-10 months to get to this point (I'd have to look at emails to be exact), but I finally have my engine built.

HKE built the longblock, on an ERL Superdeck short deck block, and Ed at Va Speed provided the ported Harrop and is in the middle of tuning it on their engine dyno.

I just hung up with him, and they did the WOT tuning last night and the engine made 710hp, and 680 ft lbs of torque. The engine is peaking at ~6k rpms. I'm ecstatic about the torque #, but slightly disappointed at the HP #. I'm not sure if I should be disappointed though, but as everyone knows, it's easy to get a # stuck in our head. When we don't get to that magic #, we start to question why. I'm not sure where the choke area is, and in fact how much of a choke it is. I'm guessing it's the Harrop, but I'm not sure how much is really left on the table. Ie: what would I gain by going to a carb manifold/tb? +'s and -'s going to a larger/different cam? I haven't gotten Shawn's opinion on the setup yet.

Engine specs:

Block: ERL Superdeck 1
Stroke: 4.250
Bore: 4.185
Heads: Performance Inductions 275cc Lsxr Titanium intake valves/ss exhaust
Intake: Ported Harrop
Cam: 247/255 112 + 2 .670 lift (int/ex the same) HUC lobes (comp cam lobe) hydraulic cam
Compression: 11.2:1


The engine is going in my Factory Five GTM now, so not the same hood issue as a Corvette or F-body.

Overall, I'm happy, but still can't wonder where the extra 40-50hp I was hoping for are. Any thoughts?

Sales4@Texas-Speed

iTrader: (4)

IMO you extra power is in the cam and compression. That is a relatively small cam for that size motor. That is still nothing to laugh at though, a motor making 700 at the crank should provide for some good times in the Factory Five GTM.

The Alchemist

iTrader: (19)

Talk to the guys at VA Speed and get their opinion since they are the ones with their hands on the motor. Find out from them what their take is. Maybe it's as simple as swapping a cam, or milling the heads/thinner gasket or going to a PI carb style intake.

Shawn @ VA Speed

iTrader: (3)

Roberto,the engine is a really big engine and requires alot of air to run high rpm-the more rpm the easier it is to make hp.The Harrop isn't designed for a large cid high rpm engine.The cross section of the runner isn't small,but isn't big either.So your kinda limited on intake airflow.Would another intake flow more air-yes,but your going to sacrifice low end,and driveability.Can we make what you have better-probably.After looking at the dyno curve-the tq drops off pretty sharply after 5000rpm,what we need to do it get this to drop off much slower-this will make more hp at the same rpm.How can we do that?-look at things like compression and cam events to gain cylinder pressure and gain more power using the same limited amount of airflow we have available.There is no one solution-or an easy one-this engine is pretty much uncharted territory.

98Z28CobraKiller

iTrader: (17)

What's the MAP sensor saying at peak power?

ATVracr

iTrader: (5)

Our motor with the same size crank and a little less bore used ALOT more cam than that !

We made a good bit more power but ours is a race motor with a single plane intake.
Yours seems like its more of a street set up, there has to be a trade off somewhere.

I bet it will be fun on the street!

Shawn @ VA Speed

iTrader: (3)

really doesn't matter since the map location isn't at the base of the runner where the smallest cross section is

Tony Mamo @ AFR

iTrader: (13)

More cam for sure....its probably about 8-10 degrees light IMO.

Big motors need alot more cam.....especially big smallblocks that usually have alot of airspeed.

I would try that first before banging your head on the wall and looking elsewhere.

Big numbers either way and the curve must be extremely fat with a lot of low midrange grunt.

Good luck hooking it up....LOL

-Tony

barkingspud

iTrader: (3)

Yep...As the experts have said. The cam is mighty small for that motor...

Stage7

iTrader: (1)

Thanks. I believe Erik is more of a fan of allowing the tuner a threshold for timing, rather than a super high compression ratio. That said, I know bumping the compression on a stock ls7 gains 20-30hp alone. Maybe half a point? Noted on the cam specs. It seems to be a common theme. I had asked Erik the same thing, and he had another cam he spec'd but he said it would only be 15hp difference, and would beat up the valves a lot more. For 15hp, I'll go with the milder cam. For 40 more hp (same torque), I'll go for the wilder cam...

Ed is going to talk with Shawn and get his opinion. It's funny, I spoke to Cary about his intake vs. the Harrop, and he didn't feel it was worth me offing the Harrop to go with his intake.

Thanks Shawn. I'm standing by for your recommendation/further thoughts on it. I know it's a unique build, especially since it still has to retain street manners. It's all a series of compromises, and they are unique to my personal tolerance vs. building a ***** to the wall race engine build. If 750hp is unstreetable, I'll stick with what I have, and hopefully Ed can find some more hp in the tune somewhere. If there is a viable solution, that is still streetable (the #1 reason I bought the Harrop intake is it's ability to tame big cams), then I'm game.

It should be fun. Any links to your build? Can you provide any info about the route you went with results?

Thanks for chiming in Tony. This is the build we discussed months ago. I'm not putting it in my Corvette now. It's going in a GTM. I'm looking forward to your build. Good luck with the results.

edcmat-l1

iTrader: (10)

I thought I could, but I lost my easy button!

98Z28CobraKiller

iTrader: (17)

DUH, forgot about the ITB.

Stage7

iTrader: (1)

It's right next to your magic wand.

I just spoke to Shawn, and he is thinking of what to do to max the combo out and maintain the Harrop. I hope to hear from him tonight or tomorrow, so hold off on the idle/drivability tune until we see what he comes up with please.

The Alchemist

iTrader: (19)

I just cracked up when I saw that. At work, I call it the CSI mentally when upper management asks why I can't get them results as quickly as they do on TV when they analyze samples.

I need to use this the next time I'm asked why it takes as long as it does to do a sample analysis.

Sorry, for the sidetrack, I thought this was histerical.

edcmat-l1

iTrader: (10)

****, I'm gettin me one LOL

http://www.staples.com/office/suppli...tNumber=606396

ATVracr

iTrader: (5)

Tall Deck RHS block
4.25 crank
4.155 bore
Cary's Mozez Heads and his intake.

Made 968hp

https://ls1tech.com/forums/nitrous-o...-ls-motor.html

98Aggie

iTrader: (19)

Borrow a different intake from someone else and dyno again. The intake is to small for that motor.

Since you have all that room in the back of the GTM a supervic with a 4500accufab TB would be killer. Might need a different cam to take advantage of the shorter runners

Stage7

iTrader: (1)

Sick build!!


I've been thinking of going that route. I could use the Harrop in my c6 (that was the original plan), or sell it. What would you guess the power difference to be?

ATVracr

iTrader: (5)

Thanks !

Cary's intakes are worth 30-50 hp over a super vic.

Stage7

iTrader: (1)

Wow...Cary didn't even want to sell me one! He didn't think it would be a big gain over the ported Harrop intake (at least with my setup-street motor).