Thread: wanted 500hp from 454

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Hi guys - I'm new here!

My pride & joy is a 1968 Iso Grifo 7-Liter, which for those who are unfamiliar, is an Italian 2-seat GT, using good old US V8 muscle. Most of the 412 built were 327-powered, but there were also some 350 small-blocks, and later on, Ford 351C. Included were 90 built with Chevy 427 or 454. They are great-looking cars, and can hold their own with contemporary Ferraris, Masers and Lambos.

I have just done a major rebuild on the engine, and generally, I am really happy with it. It gave 463hp at 5400, and 522ft lb at 3800 on the dyno.
The rotating assembly is all good stuff - forged crank, 4-bolts, Manley H-beam rods, forged 9.8:1 slugs, steel flywheel, Fluidampr - so it can take plenty of hp.
Heads are Edelbrock Performer RPM, fitted with Comp Cams beehive springs and titanium retainers (to try and beat valve-float with hydraulic roller). Carb is a Holley 750 double-pumper massaged by Chuck Nuytten of Dallas specifically for this engine, and am told it will flow up to 890cfm. Exhaust is custom stainless long 4-into-1 headers with twin 3" pipes and mufflers (sounds awesome!).
We can get 97 octane over here in England, but over 7 bucks a gallon - ouch!
Gearing is very high - 2.88 rear end with Super T-10 4-speed with a 2.88 1st gear. This car needs to top 170mph (in Germany, of course!)
However, I am very tempted to try a Tremec TKO600 5-speed with the 0.82 5th ratio and a 3.31 axle. I reckon the gearing would be about perfect then - decent acceleration and high top end.

At the moment I have a Lunati hydraulic roller, fairly mild with 218/226 @ .050", 112 deg lobe centre, and .534/.544" lift.
I feel the engine isn't as eager above 4000rpm as I would like. I would like it to feel as though it wants to race up to 5000+ rpm. So, I would like to raise the torque peak to about 4100 and hp to say, 5800.
My question (finally!) is: would a hydraulic roller of 230/236 deg @ .050", with same LC and .547/.547 lift do the trick?
I would be pleased to get nearer to 500hp, and realise the torque would probably drop to more like 500ft?

I'd be interested to hear any views!!

wow cool car!! do need a hydraulic roller cam? because i've built a 530hp 490TQ 454 before using edelbrock hydraulic flat torker cam and intake and using stock 049 and 781 oval port heads. the compression was about 9.5:1 to 10.0:1 so pump gas is the the green. if you interested in the combo let me know i'll give you the specs.

Originally Posted by grifo7

Hi guys - I'm new here!

My pride & joy is a 1968 Iso Grifo 7-Liter, which for those who are unfamiliar, is an Italian 2-seat GT, using good old US V8 muscle. Most of the 412 built were 327-powered, but there were also some 350 small-blocks, and later on, Ford 351C. Included were 90 built with Chevy 427 or 454. They are great-looking cars, and can hold their own with contemporary Ferraris, Masers and Lambos.

I have just done a major rebuild on the engine, and generally, I am really happy with it. It gave 463hp at 5400, and 522ft lb at 3800 on the dyno.
The rotating assembly is all good stuff - forged crank, 4-bolts, Manley H-beam rods, forged 9.8:1 slugs, steel flywheel, Fluidampr - so it can take plenty of hp.
Heads are Edelbrock Performer RPM, fitted with Comp Cams beehive springs and titanium retainers (to try and beat valve-float with hydraulic roller). Carb is a Holley 750 double-pumper massaged by Chuck Nuytten of Dallas specifically for this engine, and am told it will flow up to 890cfm. Exhaust is custom stainless long 4-into-1 headers with twin 3" pipes and mufflers (sounds awesome!).
We can get 97 octane over here in England, but over 7 bucks a gallon - ouch!
Gearing is very high - 2.88 rear end with Super T-10 4-speed with a 2.88 1st gear. This car needs to top 170mph (in Germany, of course!)
However, I am very tempted to try a Tremec TKO600 5-speed with the 0.82 5th ratio and a 3.31 axle. I reckon the gearing would be about perfect then - decent acceleration and high top end.

At the moment I have a Lunati hydraulic roller, fairly mild with 218/226 @ .050", 112 deg lobe centre, and .534/.544" lift.
I feel the engine isn't as eager above 4000rpm as I would like. I would like it to feel as though it wants to race up to 5000+ rpm. So, I would like to raise the torque peak to about 4100 and hp to say, 5800.
My question (finally!) is: would a hydraulic roller of 230/236 deg @ .050", with same LC and .547/.547 lift do the trick?
I would be pleased to get nearer to 500hp, and realise the torque would probably drop to more like 500ft?

I'd be interested to hear any views!!

The cam lift seems to mild to me.
I would look at hyd. roller cams in the .600 lift area to take advantage of your cylinder heads.
The duration at .050 looks about right.

Without a change in static compression ratio, you're going out of the zone for 9.8 if you go much longer than 226/234 in my opinion. Here's what I might consider for your motor. It uses lift close to what Erik likes and is ground on 112 lobe centers. http://www.cranecams.com/?show=brows...tType=camshaft

yes i think more cam like erick said. a roller cam will help do it .a roller hyd lunati like 50249 2000to6000 have the lc move out 112-114 if you want more rpm then lose the hyd roller if you want to go past 6500 them run a solid roller cam

i would like more cr 10.25:1 so to get it up to 6500 +there will be a trade off but i think it would run better with the bigger cam with the lower CR if you run it way up on rpms and is a light car. i would not run it so hard and gear for tq any ways

Thanks fellas!
I'm pleasantly surprised that you would take the time to reply with your views, which I sure appreciate.
A couple of things - I don't have any plans to exceed 6000rpm, the car is a street car after all. But it will get the occasional fun outing on the track or strip.
I read somewhere that a hydraulic roller does not start to show a clear superiority over a flat tappet cam until duration gets up around 230 deg. I am right, aren't I, that a roller cam behaves in a milder way, compared to a flat tappet with the same specs?

Thing is, I already have the hydraulic roller tappets (the expensive bit!) so I want to stick with this type of cam. The engine's staying put, so I won't be bumping compression. The 230/236 112 deg .547/.547 cam was recommended by the Comp Cams tech guy, after I explained what I wanted from the car - so I bought it. Apparently it's a jet boat grind!
But.. if it's going to run like a dog because static compression of 9.8 isn't enough, then I'll go with the Crane 226/234 that techinspector1 suggested. Will my CC cam work at all - what do you think??

One last thing - I hope there won't be any valve/piston clearance issues with the cam change?

I'll try and post a pic of the car.

Chris

good looking car . a jet boat cam will work good in a car. have used boat cams in cars and trucks .on the roller cam there is more than one reason to go to roller cam on a big block they can eat flat tappet cam . i think if you go to your second pick you will be ok with your cr . if you go to more lift you may have no piston to valve room . you may want to get that air fillter out and put a KN air fillter in

Thanks Pat,

that's what I was hoping to hear!
Yep, a K&N filter is planned. I got one that was too shallow last time.

I am running an MSD 6AL with MSD distributor, and still occasionally have a plug go out, resulting in big bangs from the exhaust! It comes back after a few miles. Plugs are NGK BP6ES (equivalent to Champion N9YC) - I wonder if they are a touch cold? Pulled a plug and it looks like it's dry-fouled, quite sooty. I do quite a bit of low-speed running getting in & out of town. Or, is it running maybe a bit rich? Jets are 73 primaries and 80 secondaries, 35 nozzle and 6.5 power valve in the primary side. Gas mileage is pretty terrible at about 10-12mpg, even when trying to be frugal!
I've ordered a set of plugs one step hotter (Splitfire SF6D). Any experience of these plugs, or other thoughts?
Thanks again,
Chris

Chris, go with the roller for sure....in my opinion, they will out-perform a flat tappet cam every time, given an equiv. duration. They can make the ramps much more agressive because of the roller instead of the flat tappet, so they cam start opening slowly, the speed up quickly...same on the closing side. Always a better choice if money allows. What kind of vacuum are you pulling with this engine? You might have to do a few carb adjustments to straighten out your plug problems. Very nice car also!!! John

the jets sound good but the power valve? check the power valve make sure you did not blow it out. with that cam you should valve good vacuum and may not need a 6.5 a stock 8.5 would work? maybe .you will not see much from the two ? how much vaccum do you have in gear at a idle and go from there i allways split the vacuum and that would be the power valve i would use so 12 would be 6 power valve and tune up or down from there . i am thinking the back is pluged? that is why the 80 jets in back?

Thanks John & Pat,

I need to do a vacuum test, although I remember the vacuum with this cam (218/226, 112 LC) is pretty good.
Interesting about the power valve - I will check it's not ruptured.
Yes, the power valve is plugged in the secondaries - is that good or can improvements be made there?
Chris

well i plug front and back the stuff i play with never as much vacuum but on yours you can keep it plug if you want should be ok on plugs i use autolites or denso

By the way,

I just managed to pick up a neat old Snap On vacuum gauge still in its original box with instructions for 15 bucks on Ebay!
When I get it, I'll measure the vacuum at idle when warmed up. Then, as Pat says, divide the reading in half and use that figure approximately to pick the correct power-valve.
A friend over here says he jazzes the motor and sees what the vacuum drops to, and then picks a power-valve just above or below that figure (I can't remember which). Does that work too?
Chris