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Peak power rpm guess?
Posted: Wed May 09, 2018 3:22 am
by Simmo
Im assembling a friends engine and looking to make peak power somewhere close to 5500-5700 to make it streetable but fun. Car is 3300lb saginaw, 3.36 rear 25" dia tyres
4.030 inverted dome pistons
3.75 stroke
10.4 compression
Professionally ported 041 heads 202/1.6 Ferrera valves
1/34 long tube headers, 2.5 mandrel bent exhaust
L48 iron intake modified as per DV with divided square bore adapter
80496 Holley with smaller float bowls to fit original aircleaner
Windage tray, scraper
Howards 110885-08 hyd roller cam 225/225/108/.525
Re: Peak power rpm guess?
Posted: Wed May 09, 2018 3:35 am
by user-30257
Simmo wrote: ↑Wed May 09, 2018 3:22 am
Im assembling a friends engine and looking to make peak power somewhere close to 5500-5700 to make it streetable but fun. Car is 3300lb saginaw, 3.36 rear 25" dia tyres
4.030 inverted dome pistons
3.75 stroke
10.4 compression
Professionally ported 041 heads 202/1.6 Ferrera valves
1/34 long tube headers, 2.5 mandrel bent exhaust
L48 iron intake modified as per DV with divided square bore adapter
80496 Holley with smaller float bowls to fit original aircleaner
Windage tray, scraper
Howards 110885-08 hyd roller cam 225/225/108/.525
What make 5500 more streetable than 6500? Even pickup trucks today have more rpm potential than that factory.
You could argue that rarely someoneone will be at 6500 but same as 5500. So really, why?
If you already have that cam, are you asking if those parts will do that?
Re: Peak power rpm guess?
Posted: Wed May 09, 2018 3:47 am
by Simmo
I dont have the cam, so was looking at an off the shelf cam.
There is enough compression to go for a cam with a higher peak. Happy to take opinions on drivability.
As its not my car Im leaning to going smaller with the cam rather than bigger after a lifetime of picking too bigger cams for my own projects.
Re: Peak power rpm guess?
Posted: Wed May 09, 2018 7:09 am
by mag2555
If you post the flow numbers on the porting work done we can take a pretty good guess on the port volume you have now and hone in closer to the answer to your question.
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 4:30 pm
by Casper393W
Just asking...do you think you will have any detonation issues with that much compression and that small of cam?
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 4:44 pm
by B Original
I come up with your specs are spot on, except I would go for a little more lift and the heads will fall a little short If you haven't done some creative porting I would shoot for 260 CFM at .550 lift I came up with 224/224/ .560 @107 LSA 520 Ft Lbs and 495 Horsepower with 13.8 Idle vacuum I don't think you can go wrong with that cam with your stated goals although you could improve a little with more lift and better heads
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 4:56 pm
by CGT
B Original wrote: ↑Wed May 16, 2018 4:44 pm
I came up with 224/224/ .560 @107 LSA 520 Ft Lbs and 495 Horsepower
520#'s out of those parts, really?
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 6:00 pm
by B Original
I didn't pay attention to the L48 Intake, considering the choke of that iron intake may hold back some potential also
I don't think it will be happy on 87 octane but let it ride with 91-93 octane and a little octane boost on hot days if the engine coolant temps want to get above 190. If all is done right I think 520 ft lbs is a realistic potential 1.35 ft lbs per cube? as long as he has good port velocity and the 041 heads has. the Hp predictions will fall short with the heads.
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 7:47 pm
by user-30257
B Original wrote: ↑Wed May 16, 2018 4:44 pm
I come up with your specs are spot on, except I would go for a little more lift and the heads will fall a little short If you haven't done some creative porting I would shoot for 260 CFM at .550 lift I came up with 224/224/ .560 @107 LSA 520 Ft Lbs and 495 Horsepower with 13.8 Idle vacuum I don't think you can go wrong with that cam with your stated goals although you could improve a little with more lift and better heads
I plugged your data into my potato. The results were exactly as you said.
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 8:08 pm
by CGT
B Original wrote: ↑Wed May 16, 2018 6:00 pm
I didn't pay attention to the L48 Intake, considering the choke of that iron intake may hold back some potential also
I don't think it will be happy on 87 octane but let it ride with 91-93 octane and a little octane boost on hot days if the engine coolant temps want to get above 190. If all is done right I think 520 ft lbs is a realistic potential 1.35 ft lbs per cube? as long as he has good port velocity and the 041 heads has. the Hp predictions will fall short with the heads.
Really comes down to the "professional" ported thing. Thats a huge variable. I guess we are likely to never know, but I would be shocked to see 1.35 on that on the dyno I use. It should be a fun street engine though OP.
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 9:58 pm
by GARY C
CGT wrote: ↑Wed May 16, 2018 8:08 pm
B Original wrote: ↑Wed May 16, 2018 6:00 pm
I didn't pay attention to the L48 Intake, considering the choke of that iron intake may hold back some potential also
I don't think it will be happy on 87 octane but let it ride with 91-93 octane and a little octane boost on hot days if the engine coolant temps want to get above 190. If all is done right I think 520 ft lbs is a realistic potential 1.35 ft lbs per cube? as long as he has good port velocity and the 041 heads has. the Hp predictions will fall short with the heads.
Really comes down to the "professional" ported thing. Thats a huge variable. I guess we are likely to never know, but I would be shocked to see 1.35 on that on the dyno I use. It should be a fun street engine though OP.
If I had to put money on it I would say 450ish tq.
Re: Peak power rpm guess?
Posted: Wed May 16, 2018 11:49 pm
by B Original
GARY C wrote: ↑Wed May 16, 2018 9:58 pm
CGT wrote: ↑Wed May 16, 2018 8:08 pm
B Original wrote: ↑Wed May 16, 2018 6:00 pm
I didn't pay attention to the L48 Intake, considering the choke of that iron intake may hold back some potential also
I don't think it will be happy on 87 octane but let it ride with 91-93 octane and a little octane boost on hot days if the engine coolant temps want to get above 190. If all is done right I think 520 ft lbs is a realistic potential 1.35 ft lbs per cube? as long as he has good port velocity and the 041 heads has. the Hp predictions will fall short with the heads.
Really comes down to the "professional" ported thing. Thats a huge variable. I guess we are likely to never know, but I would be shocked to see 1.35 on that on the dyno I use. It should be a fun street engine though OP.
If I had to put money on it I would say 450ish tq.
I can understand. a production shop that's pumping out engines is fast as a can will not put a lot of time into the details having 1.15 to 1.2 foot pounds per Cube. If an engine builder takes the time to do all the correct things I would be disappointed if the end product was to fall much below 1.3 foot pounds per Cube.
All the detales referenced have been discussed in a forum thread here somewhere
I don't think this build with the intake and heads would hurt the foot pounds near as much has a horsepower above 4500 RPMs.
It's been years since I have built with some 041 chamber style heads on a engine. Do you think the heads are the limiting ft lbs factor? My gut feeling was the heads would have a good port velocity number although the combustion chamber efficiency would hurt a few ft lbs but not 50? I have several similar 383 I've broke north of 500 ft lb several builds with 062 heads. Is there that much difference in torque between Vortec Style head's and the old fuelly designs?
Re: Peak power rpm guess?
Posted: Thu May 17, 2018 1:56 am
by GARY C
B Original wrote: ↑Wed May 16, 2018 11:49 pm
GARY C wrote: ↑Wed May 16, 2018 9:58 pm
CGT wrote: ↑Wed May 16, 2018 8:08 pm
Really comes down to the "professional" ported thing. Thats a huge variable. I guess we are likely to never know, but I would be shocked to see 1.35 on that on the dyno I use. It should be a fun street engine though OP.
If I had to put money on it I would say 450ish tq.
I can understand. a production shop that's pumping out engines is fast as a can will not put a lot of time into the details having 1.15 to 1.2 foot pounds per Cube. If an engine builder takes the time to do all the correct things I would be disappointed if the end product was to fall much below 1.3 foot pounds per Cube.
All the detales referenced have been discussed in a forum thread here somewhere
I don't think this build with the intake and heads would hurt the foot pounds near as much has a horsepower above 4500 RPMs.
It's been years since I have built with some 041 chamber style heads on a engine. Do you think the heads are the limiting ft lbs factor? My gut feeling was the heads would have a good port velocity number although the combustion chamber efficiency would hurt a few ft lbs but not 50? I have several similar 383 I've broke north of 500 ft lb several builds with 062 heads. Is there that much difference in torque between Vortec Style head's and the old fuelly designs?
It's not a build I have ever done personally I am just going off of what is more common, not saying it can't be done, I just see a lot of expectations that don't show up on the dyno, I think the heads, cam and intake for the peak power RPM will be the challenge.
Hopefully you will prove me wrong.
Re: Peak power rpm guess?
Posted: Thu May 17, 2018 4:22 am
by paulzig
CGT wrote: ↑Wed May 16, 2018 4:56 pm
520#'s out of those parts, really?
I'm thinking maybe 100LBS optimistic so more like 410HP/420TQ at 5600RPM
Re: Peak power rpm guess?
Posted: Thu May 17, 2018 5:35 am
by B Original
paulzig wrote: ↑Thu May 17, 2018 4:22 am
CGT wrote: ↑Wed May 16, 2018 4:56 pm
520#'s out of those parts, really?
I'm thinking maybe 100LBS optimistic so more like 410HP/420TQ at 5600RPM
That's just 1.09 ft lbs per? 5 years ago before I was acquainted with DV and speedtalk 1 done a 355 with 420 TQ. 465 HP with a 228 cam & 10.5-1
A moderately docile GM crate 383 is rated at 435 horsepower and 445 lb-ft of torque. At 9.4 to 1 and there's a lot of improvements to be made? Even with the Old 41 heads and the iron intake I still don't think the foot pounds are going to suffer very much.
Although I am an agreement with Gary C when he said
"the heads, cam and intake for the peak power RPM will be the challenge." The cam maybe not so much.