Slowhawk

iTrader: (12)

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.

nysbadmk8

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

Stage7

iTrader: (1)

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

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

SlickVert

iTrader: (5)

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

ExceSSive

iTrader: (13)

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...

Stage7

iTrader: (1)

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

Stage7

iTrader: (1)

dyno sheet:

Brian Tooley Racing

iTrader: (13)

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.

briannutter

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?

raymond mckinney

iTrader: (4)

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

briannutter

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.

edcmat-l1

iTrader: (10)

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.

Shawn @ VA Speed

iTrader: (3)

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

Firehawk441

iTrader: (41)

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

racer7088

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.

racer7088

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.

edcmat-l1

iTrader: (10)

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.........

racer7088

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.

vetteboy2k

iTrader: (5)

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.

Slowhawk

iTrader: (12)

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

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

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