Dynamometer Results & Comparisons - 468ci with PI 275 heads/Harrop itb-- 710hp, 680tq--missing power?

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?

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.

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.

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.

What's the MAP sensor saying at peak power?

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! :D

What's the MAP sensor saying at peak power?

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

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

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

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.

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...

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.

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.

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.

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 balls 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.

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! :D

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

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

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.

and hopefully Ed can find some more hp in the tune somewhere.

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

http://i30.photobucket.com/albums/c341/clovertime/easy-button.jpg

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

DUH, forgot about the ITB.

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

http://i30.photobucket.com/albums/c341/clovertime/easy-button.jpg

It's right next to your magic wand. :secret2:

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. :D

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

http://i30.photobucket.com/albums/c341/clovertime/easy-button.jpg

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.

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.

Shit, I'm gettin me one LOL :jest:

http://www.staples.com/office/supplies/StaplesProductDisplay?storeId=10001&catalogIdentifier=2&partNumber=606396

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



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

Made 968hp

http://www.ls1tech.com/forums/nitrous-oxide/1285511-perf-induction-briggs-prock-collaborate-maybe-baddest-nitrous-ls-motor.html

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

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

Made 968hp

http://www.ls1tech.com/forums/nitrous-oxide/1285511-perf-induction-briggs-prock-collaborate-maybe-baddest-nitrous-ls-motor.html

Sick build!!

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


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?

Thanks !

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

Thanks !

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

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).

For HP it's probly needs a bigger Cam and intake.At that point though you will probly lose drivability. Right now you probly won't hook the GTM from the broad torque curve.

For HP it's probly needs a bigger Cam and intake.At that point though you will probly lose drivability. Right now you probly won't hook the GTM from the broad torque curve.

710hp in a GTM, thats supercar beating power there.

Erik offered me another cam to swap in: 259/263 112 + 2

I'm going to speak w/Va Speed tomorrow.

Erik offered me another cam to swap in: 259/263 112 + 2

I'm going to speak w/Va Speed tomorrow.

That cam sounds a little better but still on the small size for that many cubes

It is all in what you want. Street motor or track motor. I feel your pain on the decisions involved for those compromises. I did not go that big on my motor...only 408...but you have to decide on cams/compression/intakes/exhaust.

I am not an expert, but IMO a bump in compression (11.7:1 or so) will help you with your current cam if you want to keep the smaller streetable cam that you have. Would probably bump your HP and torque, not sure how much though...

It is all in what you want. Street motor or track motor. I feel your pain on the decisions involved for those compromises. I did not go that big on my motor...only 408...but you have to decide on cams/compression/intakes/exhaust.

I am not an expert, but IMO a bump in compression (11.7:1 or so) will help you with your current cam if you want to keep the smaller streetable cam that you have. Would probably bump your HP and torque, not sure how much though...


I've thought about bumping the compression, but Erik advises against it for a street car that sees 100% pump.

dyno sheet:

http://i301.photobucket.com/albums/nn73/Stage7FD/468-dyno-HKE-VAspeed.jpg

Not to step on anyones toes, but I like to keep the overlap to 29 degrees or less, you're currently at 27 degrees, the new cam specs are 37 degrees. If you keep it low, your drivability will remain good. My cam opens the exhaust at 69 BBDC and closes the intake at 59.5 degrees ABDC. I think the early exhaust open point helps the engine pull up higher, and the later intake close point helps this also. Most people would say this type of cam doesn't make torque down low, but mine did. I hope this helps.

I wish the 4 numbers everyone spoke were intake and exhaust opening and closing points. The 4 numbers (intake/exhaust duration, lobe separation and advance) usually spoken don't mean anything to the engine. Compare Tooley's numbers to Erik's recommendation and you'll see where they're leading you.

Also, could you take a look at the cross section of the Harrop intake and report back? It's choke point may be the diameter of the barrel minus the axle cross section. I'm not sure how often Harrop updates its designs, but it didn't appear the early ones had the amount of taper seen on "race" manifolds like Kinslers, sheetmetals, or serious drag race cast single 4's like Cary's. The large taper seen on them defies the logic of commonly available formulas, but they have real world dividends. I've got $20 that says a PI or GCR 4bbl will pick that engine up 20 horsepower. Not to bash on the Harrop as it's a beautiful well made piece, but are there any 750 horsepower engines currently running them?

Robz runs one I think, not sure his power but his stick shift Zo6 runs 9.30's??

Yes, very impressive, but I don't believe he made much over 700 crank with his 388. Were there any numbers posted? His suspension, 60ft., gearing, weight, and shifting are the keys to his speed. Interestingly, he and Tooley are making similar power with TFS 245 cathedral ports. Would be neat to overlay dyno graphs with the diff. in cubes, then look at gear spacing to see what they apply down the quarter.

I've got $20 that says a PI or GCR 4bbl will pick that engine up 20 horsepower. Not to bash on the Harrop as it's a beautiful well made piece, but are there any 750 horsepower engines currently running them?

The manifold choice wasn't really about power, but rather driveability. They have the ability to calm bigger cams. Doesn't hurt that they look great too.
Everyone involved would like to see it make more power, but I don't think the owner wants to make more power at the expense of driveability.

FYI-we made 745hp with the same heads and intake on a 427

Robz runs one I think, not sure his power but his stick shift Zo6 runs 9.30's??

I've raced with Rob...
He can drive a 6 speed quite well.

It all about compromises. A larger cam will make more power on top for sure but this is mostly limited by intake cross section vs engine size. I didn't choose this manifold as I think a FAST 102 would make the same or more at a much lower price any day. Also after repairing tons of engines down here with excessive compression I wouldn't wish that on anyone that lived in an area that had good air or high amounts of heat in the summer or had to run real pump gas. This isn't a race engine it's a hydraulic roller street engine.

For comparison I helped GCRE put together an engine a week ago we dynoed down here that made 925 hp at only 8100 with smaller heads but it was a race engine with a bigger cam and 14 to 1 compression running on Q16. It also had a manifold roughly 50% bigger in CSA and therefore made a whole lot more power. We are doing another large LSx that will clear 1000 hp pretty easily as again it is a race engine and not a normal pump gas hydraulic roller deal.

FWIW I don't have much more compression on the stuff we have running low 9s on real pump gas and on one New England area customer they did step the compression on their own way up to 12 to one and didn't pickup almost anything less than one mph and of course tuning became an issue.

11.25 to one is pushing it for an engine with really high VE as pump gas varies and so do running conditions on real cars. 680 ft pounds of TQ is way high for a 468 on true pump gas already so that manifold is making very good peak VE already and going higher in compression would almost certainly result in problems. A larger cam will delay peak TQ and make more high rpm power but the entire point of this engine is to make a lot of power at lower more reliable rpms.

Anyone can make more power with almost anything short of a pro stock engine but that doesn't mean that it should or needs to be done unless it is a real race engine with no other constraints.

Not to step on anyones toes, but I like to keep the overlap to 29 degrees or less, you're currently at 27 degrees, the new cam specs are 37 degrees. If you keep it low, your drivability will remain good. My cam opens the exhaust at 69 BBDC and closes the intake at 59.5 degrees ABDC. I think the early exhaust open point helps the engine pull up higher, and the later intake close point helps this also. Most people would say this type of cam doesn't make torque down low, but mine did. I hope this helps.


Brian,

With as much VE as this engine seems to have in the middle the LSA can probably be spread a lil more to make less there and more on top for sure as well as getting bigger if that is what Roberto wants on this engine so we will do it but still this is no top end manifold at all in anyone's book.

Again I have engines here with 285+ at .050 cams in them but not on most hydraulic roller cam pump gas 11 to one engines! I think that Roberto wants more cam and more top end and now does not care if it's less nice down low at 1500 rpm so that's where we will go. It's all up to the customer as far as how wild they want to go.

Remember I have a mid 11 to one deal with your TFS235s untouched on it with a FAST 90 that makes around this power and goes lower 9s and yes it has a bigger cam since its a higher stall auto car that is only drag raced. It is not as compromised though as it has only one main purpose.

It's about to get bigger heads from you guys and a much bigger manifold and go almost 8s on pump gas and hydraulic roller. The main change though will be the much larger manifold. I think I will pickup another 60 hp over the FAST 90 easily or more.

With as much VE as this engine seems to have in the middle the LSA can probably be spread a lil more to make less there and more on top for sure as well as getting bigger if that is what Roberto wants on this engine so we will do it but still this is no top end manifold at all in anyone's book.


These manifolds do have incredible VE through the midrange. You can see it in the tuning.

I don't know if Roberto really wants it any more radical than it is, he just would have liked better numbers as is. That seems to be the deal with everyone. No offense to anyone. Just the way it goes.........

These manifolds do have incredible VE through the midrange. You can see it in the tuning.

I don't know if Roberto really wants it any more radical than it is, he just would have liked better numbers as is. That seems to be the deal with everyone. No offense to anyone. Just the way it goes.........

Yep I see and deal with this almost every engine that goes out to anyone else to tune. It's a compromise and I agree with nearly all the advice Shawn gave Roberto except we never run as much as compression as other shops do and that's part of the reason we probably still have the reputation we do.

Roberto's deal power to weight at 700 hp at only 6000 rpm is enough to run into the 8s and over 150 in the quarter which is quite a lot for a 6500 rpm hydraulic roller pump gas deal that should last a good long time. The bigger inches and Harrop both make for outstanding lower rpm and midrange power and still some decent top end in reality.

Yes, very impressive, but I don't believe he made much over 700 crank with his 388. Were there any numbers posted? His suspension, 60ft., gearing, weight, and shifting are the keys to his speed. Interestingly, he and Tooley are making similar power with TFS 245 cathedral ports. Would be neat to overlay dyno graphs with the diff. in cubes, then look at gear spacing to see what they apply down the quarter.

Rob's car was making around 700+rwhp with the Harrop last year. Although the harrop is not the ideal drag race manifold and high rpm manifold it surprisingly works quite well and you can't beat it's street manners.

Harrop has not update their design. Larger diameter trumpets would be better for bigger cubed motors for sure and a taper couldn't hurt but we really feel the Harrop is not the choke point here. As Ed H. knows, the Harrop needs to be ported alot to help line up with heads and strighten out runner. IMO there are several intrinsic problems with all of the mITB manifolds out there but that's for a different discussion. It's hard to please all buyers and that's why we have custom intakes.
The harrop seems like a great choice for RR and can tame a big cam making it very driveable.
To the owner: I'd drive it and race it in it's current configuration because at that weight the car will be a rocket and you might not want more power. You have a great team behind you.

These manifolds do have incredible VE through the midrange. You can see it in the tuning.

I don't know if Roberto really wants it any more radical than it is, he just would have liked better numbers as is. That seems to be the deal with everyone. No offense to anyone. Just the way it goes.........

Up here we call that the "big dick' "tight ass" syndrome.

big dick -high dyno graph(peak #'s only)

tight ass- complaining when there high hp drive's like crap around town.

:D

Yep I see and deal with this almost every engine that goes out to anyone else to tune. It's a compromise and I agree with nearly all the advice Shawn gave Roberto except we never run as much as compression as other shops do and that's part of the reason we probably still have the reputation we do.

Roberto's deal power to weight at 700 hp at only 6000 rpm is enough to run into the 8s and over 150 in the quarter which is quite a lot for a 6500 rpm hydraulic roller pump gas deal that should last a good long time. The bigger inches and Harrop both make for outstanding lower rpm and midrange power and still some decent top end in reality.


Thanks for adding to the thread Erik.


Rob's car was making around 700+rwhp with the Harrop last year. Although the harrop is not the ideal drag race manifold and high rpm manifold it surprisingly works quite well and you can't beat it's street manners.

Harrop has not update their design. Larger diameter trumpets would be better for bigger cubed motors for sure and a taper couldn't hurt but we really feel the Harrop is not the choke point here. As Ed H. knows, the Harrop needs to be ported alot to help line up with heads and strighten out runner. IMO there are several intrinsic problems with all of the mITB manifolds out there but that's for a different discussion. It's hard to please all buyers and that's why we have custom intakes.
The harrop seems like a great choice for RR and can tame a big cam making it very driveable.
To the owner: I'd drive it and race it in it's current configuration because at that weight the car will be a rocket and you might not want more power. You have a great team behind you.

Robz's car was definitely one of my main inspirations for the build. Seeing the youtube vid of his car idling at 650rpm, and click off a 9sec quarter mile at over 140mph NA/street gas was amazing. He probably knows more about these Harrop's in the real world street/racing conditions than Harrop.

Va Speed ported the Harrop for me. As far as I know, it's ported as much as it can be ported. When the car and engine are back in Jersey I would like to come with you guys to a track day. I just picked up a transaxle last night that should have no issues holding this torque with sticky tires on a semi-hard launch. I'm not sure how the gearing ratio's of a Porsche 997 (11 TT gear box will pan out with 26" tires....but we will see what it'll do regardless. Interestingly the Porsche 911 TT peaks at the EXACT same rpm as my motor does. 5k for torque, and 6k for hp and the Porsche has a 6600rpm redline. In fact with it's variable vane turbos it makes close to peak torque below 2k rpm and carries it about flat to 5k. Insane.

Thanks for the advice...it's very sound. I should probably enjoy it as is. The car will be a death trap as is. But we are all in this hobby to get the most we can within our combo's tolerance, and respective budgets. lol Otherwise we would all be driving factory spec cars.

The reason I created this thread was for feedback on the results considering the combo from people with more experience than me. I admit to being slightly disappointed at the 710hp # when I initially heard it, but again I wasn't sure if I SHOULD have any disappointment considering the combo/constraints placed on the build (Harrop, streetable, pump gas, reliable).

In fact the more I've read, learned, and spoken to people about it, I'm actually happy with the results. Going into this I really didn't know what to expect #'s wise as it hasn't really been done. I allowed myself to get caught up in the #'s game of people running a point or more of compression, much larger cams, different intakes, etc a little bit too.


Would I like more hp? Of course, who wouldn't...the nice thing is more hp is a manifold and/or cam swap away.

Regardless of peak #'s moving the powerband to the right may make the car slightly easier to drive fast though.

I appreciate people's thoughts and opinions on the combo, as well as sharing their experiences. I've gained some helpful insight.

Even more I appreciate Erik's humility (as well as the bad ass engine he built) as I spoke to him first before posting about the engine/cam specs, etc. He had zero issue giving out cam specs, nor posting/discussing on the internet about the combo/results. He is not only the best engine builder in the biz, but a downright good guy. Not too many in this hobby unfortunately. He isn't the fastest builder, lol...but he's made a customer for life.

The manifold choice wasn't really about power, but rather driveability. They have the ability to calm bigger cams. Doesn't hurt that they look great too.
Everyone involved would like to see it make more power, but I don't think the owner wants to make more power at the expense of driveability.

True Ed, the Harrop's ability to tame big cams while making great power was the #1 reason for the choice. Thanks for all of the time you've spent answering questions and your work tuning it. I appreciate it. I hope you find some more power tonight with it.

Well, Ed is about finished the itb adjustments, and idle/drivability tuning on the motor. It's idling at 800rpm, just about dead smooth according to Ed. He is going to send some pix, and try and get a short video clip of it idling.