Want to make more power then add more air and fuel. 
HPR 468 peaking to low.
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From: Lawrenceburg Ky
HPR 468 peaking to low. My 468 finally made it to the dyno this week and made great numbers and no I won't share them so don't ask. My concern is that it's peaking at only 6500. I was hoping to peak around 7000. Would stepping up to a CID intake and 4500 throttlebody get me where I need to be?
Specs:
HPR 468, 13.5 compression, Tony Mamo Heads 265 heads, hydraulic roller cam 675/.675 lift 262/276 duration 114+4 lobe sep, Carbon PST intake, Holley 105mm throttlebody, 2" headers, E85.
Specs:
HPR 468, 13.5 compression, Tony Mamo Heads 265 heads, hydraulic roller cam 675/.675 lift 262/276 duration 114+4 lobe sep, Carbon PST intake, Holley 105mm throttlebody, 2" headers, E85.
Last edited by BigDaddy97; Jul 11, 2021 at 04:43 PM.
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my 454 solid roller mamo heads , 255/269 with mamo ported msd peaks at 6540rpm, at 7000rpm its 10rwhp down from peak.
WIth your cam specs being 10 degrees more, hyd to solid, youd think your peak would be higher..
Ive seen a few threads on CF where guys with big cube engines were swapping out intakes from mamo msd trying to get more revs/hp but none of them got much more.
i hvnt tried myself tho so only relaying wht if read
WIth your cam specs being 10 degrees more, hyd to solid, youd think your peak would be higher..
Ive seen a few threads on CF where guys with big cube engines were swapping out intakes from mamo msd trying to get more revs/hp but none of them got much more.
i hvnt tried myself tho so only relaying wht if read
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From: Lawrenceburg Ky
my 454 solid roller mamo heads , 255/269 with mamo ported msd peaks at 6540rpm, at 7000rpm its 10rwhp down from peak.
WIth your cam specs being 10 degrees more, hyd to solid, youd think your peak would be higher..
Ive seen a few threads on CF where guys with big cube engines were swapping out intakes from mamo msd trying to get more revs/hp but none of them got much more.
i hvnt tried myself tho so only relaying wht if read
WIth your cam specs being 10 degrees more, hyd to solid, youd think your peak would be higher..
Ive seen a few threads on CF where guys with big cube engines were swapping out intakes from mamo msd trying to get more revs/hp but none of them got much more.
i hvnt tried myself tho so only relaying wht if read
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An issue is the 4500 may pick up you rpm and peak a little higher.but lose a lot of power under the curve. Did you have any performance goals for the car? Likely no one could give you better info than Erik himself when it comes to his 468’s and most of the purpose
of the cubes is to keep the valve train happier for longer and netting power from that rather than turn a 427 or 440 tighter.
of the cubes is to keep the valve train happier for longer and netting power from that rather than turn a 427 or 440 tighter.
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From: Lawrenceburg Ky
An issue is the 4500 may pick up you rpm and peak a little higher.but lose a lot of power under the curve. Did you have any performance goals for the car? Likely no one could give you better info than Erik himself when it comes to his 468’s and most of the purpose
of the cubes is to keep the valve train happier for longer and netting power from that rather than turn a 427 or 440 tighter.
of the cubes is to keep the valve train happier for longer and netting power from that rather than turn a 427 or 440 tighter.
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From: Melbourne, Australia
Good point with map... I have a tpis 102mm tb and at wot I’m 99.5kpa.. my peaks at 6500 coz of long runners in msd intake.... few people on CF who are shortening the runners and picking up 400rpm up too
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what's your idea?
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I just heard back from HPR. They did do a test with the CID, Eric said I would pick up about 50 rwhp and several hundred rpm with the CID over the Carbon PST.
Last edited by BigDaddy97; Jul 11, 2021 at 10:44 PM.
Your map value will fall off at higher rpm if your intake is a choke point....i.e. you'll read more vacuum.
my car has a 1.80 glide also and a coan 6k stall. hydraulic roller n/a with a 102 mm tb, sounds pretty similar to yours. Run it at the track before you worry too much about dyno numbers.
They do make bigger throttle bodies. May as well just slap one on and try it. My guess is you are correct, it's a choke of some point. Could be valvetrain going nuts, but would probably show it on the dyno different. When you are at the level you are at, change one thing at a time and test. Data is you friend.
Could be a plenum volume problem, as well. Do they make a spacer for the lid? Did anyone do a volume calc on what the motor needs? Plenum volume is different than total intake volume, but the two affect each other. Example, I have worked on old school big blocks that ended up flying w/ a way too big carb(Holley Hp1000) on a ported stock iron intake and worked great. Ask anyone, combo was all wrong, lol. The super high air speed and lack of plenum volume created a perffect storm for huge carburation and drove really well and made stupid power for what it was. Basically,, plenum volume needs to be sufficient to feed the "pulse" when the valve opens. Not enough and it starts to feed from the inlet source(carb/TB). It's a balancing act, especially on big motors like yours. That intake was designed around a 400-427in motor, not making the VE yours is. Unless Eric already worked his magic, I am sure there is power there, just playing w/ what you already have. A call to Hogan's may shed light.
Could be a plenum volume problem, as well. Do they make a spacer for the lid? Did anyone do a volume calc on what the motor needs? Plenum volume is different than total intake volume, but the two affect each other. Example, I have worked on old school big blocks that ended up flying w/ a way too big carb(Holley Hp1000) on a ported stock iron intake and worked great. Ask anyone, combo was all wrong, lol. The super high air speed and lack of plenum volume created a perffect storm for huge carburation and drove really well and made stupid power for what it was. Basically,, plenum volume needs to be sufficient to feed the "pulse" when the valve opens. Not enough and it starts to feed from the inlet source(carb/TB). It's a balancing act, especially on big motors like yours. That intake was designed around a 400-427in motor, not making the VE yours is. Unless Eric already worked his magic, I am sure there is power there, just playing w/ what you already have. A call to Hogan's may shed light.
Last edited by DualQuadDave; Jul 11, 2021 at 09:54 PM.
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From: Lawrenceburg Ky
They do make bigger throttle bodies. May as well just slap one on and try it. My guess is you are correct, it's a choke of some point. Could be valvetrain going nuts, but would probably show it on the dyno different. When you are at the level you are at, change one thing at a time and test. Data is you friend.
Could be a plenum volume problem, as well. Do they make a spacer for the lid? Did anyone do a volume calc on what the motor needs? A call to Hogan's may shed light.
Could be a plenum volume problem, as well. Do they make a spacer for the lid? Did anyone do a volume calc on what the motor needs? A call to Hogan's may shed light.
I would think I've got plenty of plenum volume with this intake, it's huge.
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From: Lawrenceburg Ky
Trust me, I know what it is. Planning on one myself in the not too distant future. Still need to do the calc. I would bet on the TB being the problem, though. Have seen smaller combos than yours pick up w/ a 108/112mm NA.
I agree with this advice. Go do a test and tune night before you make changes. See how it goes down the track, and then make changes in steps. I’d go stall first and then try a gear change if needed. It will like a bigger TB undoubtedly. Don’t focus on the dyno numbers so much. A dyno is a tuning tool…that’s about it.
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I agree with this advice. Go do a test and tune night before you make changes. See how it goes down the track, and then make changes in steps. I’d go stall first and then try a gear change if needed. It will like a bigger TB undoubtedly. Don’t focus on the dyno numbers so much. A dyno is a tuning tool…that’s about it.