can you guys post up your 408 results/setups here?
Originally Posted by kumar75150
damn i need to learn how to figure out dynamic compression
im guessing with my 253/261 on a 113 cam, i could prolly run quite a bit of compression
im guessing with my 253/261 on a 113 cam, i could prolly run quite a bit of compression
TECH Fanatic
Joined: Mar 2003
Posts: 1,112
Likes: 0
From: Dallas
Originally Posted by 383ss
its pretty easy to find a calculator, just do a search on here or on google. just have to know your ABDC cam info
i lost the damn cam card
Originally Posted by kumar75150
I just remember its a 253 261 with about .645 lift on a 113
i lost the damn cam card
i lost the damn cam card
Also, I'm assuming a 50 deg separation from .006" to .050" which is what the LSK lobe is and the .645" lift seems close to an LSK lobe. But, if you want to run anything over 12.1:1+ you need a spot on tune (timing and A/F), good quench, and at least 92 octane regardless of the cam. Also, another important thing to remember is an upgraded cooling system. Really high DCR makes a lot of heat and with a 408, it can really tax a stock cooling system. So that's another thing to consider if you want to fend off detonation.
TECH Fanatic
Joined: Mar 2003
Posts: 1,112
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From: Dallas
Originally Posted by JakeFusion
You can estimate the advertised duration to guesstimate. I'd say around 301-305 intake and 309-313 exhaust. After figuring the ABDC which is around ~84.5 if on a 113 ICL, seems like you can run 12.8:1 without much problem. If my numbers are in the right ballpark, you could run even a little more, but if you don't know for sure, I wouldn't push it. In fact, I'd get it cam doctored before running anything close to that.
Also, I'm assuming a 50 deg separation from .006" to .050" which is what the LSK lobe is and the .645" lift seems close to an LSK lobe. But, if you want to run anything over 12.1:1+ you need a spot on tune (timing and A/F), good quench, and at least 92 octane regardless of the cam. Also, another important thing to remember is an upgraded cooling system. Really high DCR makes a lot of heat and with a 408, it can really tax a stock cooling system. So that's another thing to consider if you want to fend off detonation.
Also, I'm assuming a 50 deg separation from .006" to .050" which is what the LSK lobe is and the .645" lift seems close to an LSK lobe. But, if you want to run anything over 12.1:1+ you need a spot on tune (timing and A/F), good quench, and at least 92 octane regardless of the cam. Also, another important thing to remember is an upgraded cooling system. Really high DCR makes a lot of heat and with a 408, it can really tax a stock cooling system. So that's another thing to consider if you want to fend off detonation.
Ill post some numbers when its all put together.I have a high compression solid roller motor over 700 lift and the duration is in the 27? 28? range just need my ETP heads and ill be all set.I also have a gm single plan intake with a accel 1550 cfm throttle body. 
Topped off with a pro race DP nitrous kit and a plate system to boot. 
Topped off with a pro race DP nitrous kit and a plate system to boot. 
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
Originally Posted by tuff
Ill post some numbers when its all put together.I have a high compression solid roller motor over 700 lift and the duration is in the 27? 28? range just need my ETP heads and ill be all set.I also have a gm single plan intake with a accel 1550 cfm throttle body. Topped off with a pro race DP nitrous kit and a plate system to boot.
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Finally got my new heads and Kooks headers on and got some dyno results. I put down 472 rwhp on our Mustang dyno. I think the torque was 430ish if I remember right. I'm pretty happy with that considering it is through a loose converter/th400. I look forward to getting it on the track and seeing how it compares to last years times. Haven't sprayed it on the dyno yet - wanted to get the motor tune in good first.
Originally Posted by str8evl
what I am looking to do is a 402 or 408 with a 90/90, et 245's, powerglide to a 9". Everything is set in stone other than the heart (the motor). So that being said, is 6 cubes worth the weight on the nose? I have so many questions on these motors that have yet to be fully answered in any of forums I visit. This being the tech site, of course the info i get here is the most informational. keep this thread alive and you guys that are already running these motors keep the info rolling because there is alot of us doing a balancing act on the eternal question what motor? 
Time to bring this thread back... Why do I have so much lower numbers with my setup than everyone else with 408's? My setup is:
My current specs are as follows:
HPE 408
11:1 SCR
244/248 635/627 112 (installed 4 degrees advanced for the restrictive heads)
Eagle crank
Callies rods
Diamond flat top pistons w/ 2cc reliefs
Stock 6.0 heads (317)
SVO 42 #'s
LS6 intake
P/P stock TB
Edelbrock 1 7/8 stepped LT's/ORY
LM catback
Made 425/445 with 12.1-12.9 AFR. Supposedly nothing substantial was gained by leaning it out. I thought my numbers were decent until perusing this thread. Any ideas?
I'm sending my heads out tomorrow to get ported and a 2.08/1.6 setup so that should help a bit. But I'd like to get the lost power issue addressed now before the heads get back so I don't have to extend this issue
My current specs are as follows:
HPE 408
11:1 SCR
244/248 635/627 112 (installed 4 degrees advanced for the restrictive heads)
Eagle crank
Callies rods
Diamond flat top pistons w/ 2cc reliefs
Stock 6.0 heads (317)
SVO 42 #'s
LS6 intake
P/P stock TB
Edelbrock 1 7/8 stepped LT's/ORY
LM catback
Made 425/445 with 12.1-12.9 AFR. Supposedly nothing substantial was gained by leaning it out. I thought my numbers were decent until perusing this thread. Any ideas?
I'm sending my heads out tomorrow to get ported and a 2.08/1.6 setup so that should help a bit. But I'd like to get the lost power issue addressed now before the heads get back so I don't have to extend this issue
You're down a good 40rwhp if its an M6. The heads shouldnt be that much of a restriction when people are putting down 460+ with stock heads and the LS6 intake.
I don't think the cam is the problem, as you should be peaking around 6100-6200 or so with it, meaning great power under the curve as you aren't fightning against what the intake manifold will restrict you too. However, I would install it straight up on 112 ICL just to see if you can gain anything that way.
Also, your compression is too low. I'm sure the .006" duration on that cam is very large at near 300/305 or so. Even with the advance, 11.1:1 is simply too low a static compression. And if you retard the cam at all, your DCR will simply fall even more. Since the 408 is big, it can use a big cam. And big cams need lots of compression. In fact, I would not recommend running a 400+cid stroker without at least an 11.7:1 SCR. Even for 91 octane, you will not have a problem if you keep the DCR less than 8.2:1. 93 octane should stay around 8.5:1. More can be run, but you need to make sure you have the cooling system and the tune to ensure proper operation.
I don't think the cam is the problem, as you should be peaking around 6100-6200 or so with it, meaning great power under the curve as you aren't fightning against what the intake manifold will restrict you too. However, I would install it straight up on 112 ICL just to see if you can gain anything that way.
Also, your compression is too low. I'm sure the .006" duration on that cam is very large at near 300/305 or so. Even with the advance, 11.1:1 is simply too low a static compression. And if you retard the cam at all, your DCR will simply fall even more. Since the 408 is big, it can use a big cam. And big cams need lots of compression. In fact, I would not recommend running a 400+cid stroker without at least an 11.7:1 SCR. Even for 91 octane, you will not have a problem if you keep the DCR less than 8.2:1. 93 octane should stay around 8.5:1. More can be run, but you need to make sure you have the cooling system and the tune to ensure proper operation.
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From: Chitown-Jax NC-Jax FL-Honolulu-OKC, OK-NOW New Orleans Area
Food for thought on the intake etc.... Granted I am learning more and more by the day. What I have read and been told by many is that:
1- 90/90 set up is best
2- 1 7/8 LT best
3- Either AFR, 6.0 heads, good sets of lg heads are really good
4- Good tune
but each is their own.
I know I got the 90/90, 1 7/8 LT off road Y, Stage 3 6.0 heads. Tune is in the begining stages
1- 90/90 set up is best
2- 1 7/8 LT best
3- Either AFR, 6.0 heads, good sets of lg heads are really good
4- Good tune
but each is their own.
I know I got the 90/90, 1 7/8 LT off road Y, Stage 3 6.0 heads. Tune is in the begining stages
Originally Posted by GrannySShifting
Those extra cubes arent going to make you a any more power. Its strength block integrity and rebuildableness (mmm maybe thats a word) that would make us make the choice for a customer. If your staying on the motor, aluminum wouldnt kill ya. Is this Str8evl from EFA? Long time no see man!
I would go aluminum and keep the 100lbs off the nose. the 6 cubes will only make you about 6 more rwhp.
Originally Posted by JakeFusion™
You're down a good 40rwhp if its an M6. The heads shouldnt be that much of a restriction when people are putting down 460+ with stock heads and the LS6 intake.
I don't think the cam is the problem, as you should be peaking around 6100-6200 or so with it, meaning great power under the curve as you aren't fightning against what the intake manifold will restrict you too. However, I would install it straight up on 112 ICL just to see if you can gain anything that way.
Also, your compression is too low. I'm sure the .006" duration on that cam is very large at near 300/305 or so. Even with the advance, 11.1:1 is simply too low a static compression. And if you retard the cam at all, your DCR will simply fall even more. Since the 408 is big, it can use a big cam. And big cams need lots of compression. In fact, I would not recommend running a 400+cid stroker without at least an 11.7:1 SCR. Even for 91 octane, you will not have a problem if you keep the DCR less than 8.2:1. 93 octane should stay around 8.5:1. More can be run, but you need to make sure you have the cooling system and the tune to ensure proper operation.
I don't think the cam is the problem, as you should be peaking around 6100-6200 or so with it, meaning great power under the curve as you aren't fightning against what the intake manifold will restrict you too. However, I would install it straight up on 112 ICL just to see if you can gain anything that way.
Also, your compression is too low. I'm sure the .006" duration on that cam is very large at near 300/305 or so. Even with the advance, 11.1:1 is simply too low a static compression. And if you retard the cam at all, your DCR will simply fall even more. Since the 408 is big, it can use a big cam. And big cams need lots of compression. In fact, I would not recommend running a 400+cid stroker without at least an 11.7:1 SCR. Even for 91 octane, you will not have a problem if you keep the DCR less than 8.2:1. 93 octane should stay around 8.5:1. More can be run, but you need to make sure you have the cooling system and the tune to ensure proper operation.
DCR is around 7.8:1 if it's advanced 4 degrees. Take that out and it's very weak at 7.4:1. You have to figure a half point of DCR is worth nearly 5% and that means you're looking at over 20rwhp being left on the table.
I understand the concern about 90 degree summers, but I don't have a problem in Florida when its 95 and humid to the point where you have to turn on windshield wipers to see to drive. I keep the DCR right at 8.5:1.
I understand the concern about 90 degree summers, but I don't have a problem in Florida when its 95 and humid to the point where you have to turn on windshield wipers to see to drive. I keep the DCR right at 8.5:1.
