BigDaddy97

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.

01CamaroSSTx

iTrader: (3)

Your asking a question with that opening statement... Want to make more power then add more air and fuel.

Mickyinks

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

BigDaddy97

I'm also only dropping 10 horsepower from 6500 to 7000. It's almost a total flatline which makes me think the 105 throttlebody isn't feeding it enough air. A 4500 should solve that problem.

onebadbowtie86

iTrader: (13)

should be able to tell from the map values if the 105 mm tb was a restriction or not. I will be somewhat surprised if it is.

Summitracing

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.

BigDaddy97

Right, I've sent a pm to Eric and waiting to hear back. My setup is pure drag truck that will run well into the 9's in the 1/4. FTI did the stall which is an 8" 6000 with a 1.80 powerglide. I'm afraid it will be a turd with 6500 peak power on a 6000 stall.

Summitracing

Understood. It would be curious if it ran harder with a 5500 or pulling a longer gear but a trip to the track will be pretty telling. You are in good hands for sure.

Mickyinks

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

Fishmasterdan

curious how the map would tell you this? I suppose if you took a non running reading then compared it to a pass you would be able to see a vaccuum difference.
what's your idea?

BigDaddy97

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.

ddnspider

iTrader: (26)

Your map value will fall off at higher rpm if your intake is a choke point....i.e. you'll read more vacuum.

onebadbowtie86

iTrader: (13)

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.

DualQuadDave

iTrader: (6)

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.

NAVYBLUE210

With that long stroke 4.30s may be your friend VS 4.56s.
After some testing with current combo at track of course.

BigDaddy97

I would think I've got plenty of plenum volume with this intake, it's huge.

BigDaddy97

Hi Dan, I actually have 4.10s in it now but have 4.30s in reserve if need be.

DualQuadDave

iTrader: (6)

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.

Che70velle

iTrader: (6)

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.

BigDaddy97

Lol.....with you on this, I'm that guy who doesn't give 2 craps about a dyno number. I'm only concerned about my peak rpm.