Were did I go wrong with my engine combo
12 Second Club
Joined: Dec 2017
Posts: 1,030
Likes: 219
From: San Antonio
Wow. It might be possible to get 500 Whp out of an NA LS1, but it's probably not gonna be very streetable. It would have been easier and probably cheaper to get 500 Whp with a supercharger. The supercharger would be a lot more streetable too.
I BUILT a 500 rwhp Ls1 stock bottom end. It was streetable but barely.
On your cam, 224 will not be enough. It is a great cam for a 5.7 but on a 383 it would be mild. 237/245 would be about ideal for your 383. That is my cam that hit 500. In a 383 it will drive easier. 242/250 is big. On a 113 you may not have enough dynamic compression causing it to feel like a dog. Which is why I asked about your compression ratio.
To carry up top you may need a shorter runner intake. That fast is going to force the peak to 6300 or close to it. RPM is HP.
Your torque should be more like 470. Get your dynamic compression up and you can get there. If your torque is 470 and you carry power better you can clear 500.
PM if you want me to go into more detail.
On your cam, 224 will not be enough. It is a great cam for a 5.7 but on a 383 it would be mild. 237/245 would be about ideal for your 383. That is my cam that hit 500. In a 383 it will drive easier. 242/250 is big. On a 113 you may not have enough dynamic compression causing it to feel like a dog. Which is why I asked about your compression ratio.
To carry up top you may need a shorter runner intake. That fast is going to force the peak to 6300 or close to it. RPM is HP.
Your torque should be more like 470. Get your dynamic compression up and you can get there. If your torque is 470 and you carry power better you can clear 500.
PM if you want me to go into more detail.
I built an 383 ls1 trickflow 220s Fast 102 intake /tb tsp custom grind cam speced for my engine, 242/250 duration / .365/.353 -.620/.600 @ 113 lobe separation 1&17/8 long tubes and full tsp duel exhaust , yank 3600 stall. 9in with 3:89 gears , my t/a made 448/430 to the ground on a dyno jet , they tuned it speed density , the car feels real gutless driving around, won’t idle, even @ wot car feel like a dog , could it be the tune or is it over cammed? I called BTR the other day and they recommend there stage 4 cam .
Are the heads as cast out ifcthe box do have additional port work, custom valve job etc?
Exactly who spec'd the custom cam? Not everyone doing custom cams has a clue. Your cam has 20 degrees of overlap. For your goal of daily driving, that doesn't seem like a the best choice. For drag strip it's probably a very good .
Fwiw -Consulting several experts on cams, seemed like ~236 to 238 degrees on intake lobe duration is pretty good for street/strip 383's. The new cam I've considered for my 383 is a Land Speed Cylinder Heads custom Bullet Cams grind that's roughly 236/242 it has ~ 15 degrees overlap, drives well and makes excellent power.
The soft and gutless feel sounds like the tune isn't right. Despite the soft feel your car may run fantastic in the 1/4 mile - feel can be deceiving.
My LS1 383, has a small 229/229 cam, TEA LS6 2.5 heads, 90mm snout LS6, T56, 465 whp, 442wtq drives like stock. Car drives very crisp and responsive even farting around at 1,200 rpm. The car comes "on the cam" at 4,800 rpm and pulls hard, shift at 6,500 rpm.
The drive ability issues are probably a combo of tuner and fast 102 tb. A Nick Williams TB or even a WARR 102 TB will probably tune easier and drive better.
My gut feeling is it's 50 percent needs more/better Tuning& 50 perfect Fast TB issues.
Best wishes sorting the car out to optimal potential.
Thread Starter
Staging Lane
Joined: Dec 2017
Posts: 90
Likes: 6
From: Wapwallopen pa
A few questions and comments.
Are the heads as cast out ifcthe box do have additional port work, custom valve job etc?
Exactly who spec'd the custom cam? Not everyone doing custom cams has a clue. Your cam has 20 degrees of overlap. For your goal of daily driving, that doesn't seem like a the best choice. For drag strip it's probably a very good .
Fwiw -Consulting several experts on cams, seemed like ~236 to 238 degrees on intake lobe duration is pretty good for street/strip 383's. The new cam I've considered for my 383 is a Land Speed Cylinder Heads custom Bullet Cams grind that's roughly 236/242 it has ~ 15 degrees overlap, drives well and makes excellent power.
The soft and gutless feel sounds like the tune isn't right. Despite the soft feel your car may run fantastic in the 1/4 mile - feel can be deceiving.
My LS1 383, has a small 229/229 cam, TEA LS6 2.5 heads, 90mm snout LS6, T56, 465 whp, 442wtq drives like stock. Car drives very crisp and responsive even farting around at 1,200 rpm. The car comes "on the cam" at 4,800 rpm and pulls hard, shift at 6,500 rpm.
The drive ability issues are probably a combo of tuner and fast 102 tb. A Nick Williams TB or even a WARR 102 TB will probably tune easier and drive better.
My gut feeling is it's 50 percent needs more/better Tuning& 50 perfect Fast TB issues.
Best wishes sorting the car out to optimal potential.
Are the heads as cast out ifcthe box do have additional port work, custom valve job etc?
Exactly who spec'd the custom cam? Not everyone doing custom cams has a clue. Your cam has 20 degrees of overlap. For your goal of daily driving, that doesn't seem like a the best choice. For drag strip it's probably a very good .
Fwiw -Consulting several experts on cams, seemed like ~236 to 238 degrees on intake lobe duration is pretty good for street/strip 383's. The new cam I've considered for my 383 is a Land Speed Cylinder Heads custom Bullet Cams grind that's roughly 236/242 it has ~ 15 degrees overlap, drives well and makes excellent power.
The soft and gutless feel sounds like the tune isn't right. Despite the soft feel your car may run fantastic in the 1/4 mile - feel can be deceiving.
My LS1 383, has a small 229/229 cam, TEA LS6 2.5 heads, 90mm snout LS6, T56, 465 whp, 442wtq drives like stock. Car drives very crisp and responsive even farting around at 1,200 rpm. The car comes "on the cam" at 4,800 rpm and pulls hard, shift at 6,500 rpm.
The drive ability issues are probably a combo of tuner and fast 102 tb. A Nick Williams TB or even a WARR 102 TB will probably tune easier and drive better.
My gut feeling is it's 50 percent needs more/better Tuning& 50 perfect Fast TB issues.
Best wishes sorting the car out to optimal potential.
TECH Fanatic
Joined: Jan 2017
Posts: 1,758
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This is so easy to solve. Cam is too big for your application and use. Smaller cam will make it feel way better. I'd wager it would be faster at the track too. Those heads are very good and don't need a big cam to make good track times.
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Brett Foote
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
Which then makes sense.
Originally Posted by Rickys2003svt.cobra
The heads are trickflow 220 as cast. I bought em bare installed 2.055 / 1.57 Manley valves , Texas speed speced the cam , I did tell them it was a street car when I ordered my cam intake and roller rockers from them , as for the throttle body the car will idle all day long it’s just comeing a stop it’s an nightmare have to step on the brake and gas to keep it running, the compression ratio is 11:4 , I have no problem buying a new cam for the car , but what cam should I go with that will work the best with my engine/ heads combo
TECH Veteran
Joined: Sep 2014
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From: Mississippi
You don't think a 383ci STROKER could use more duration than that ? I certainly do. I honestly think this is why we dont see 383ci LS motors PERFORM the way they should. I think guys FORGET stroke eats duration and they undercam the motor. After all we see guys running 23X cams in ls1 motors thats not stroke. I personally would cam a 383 the same as a 402 cubic inch motor....
TECH Fanatic
Joined: Jan 2017
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Clearly it doesn't need more duration because it has poor part throttle response and idle quality with the cam in it now. You can't tune out overlap. Any self respecting cam company will not recommend a cam of that size for his application for street use.
TECH Veteran
Joined: Sep 2014
Posts: 4,892
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From: Mississippi
Car could have a poor tune as well. I went threw 3 different tuners myself before I was happy. My cam is a 229/244 duration.
TECH Apprentice
Joined: Apr 2019
Posts: 365
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From: California
I was watching Sloppy Mechanics to get some ideas in case I decide to swap a cam in my '01 Camaro. My suggestion is to do a bit more research to find a streetable cam for your 383. The lift isn't a problem, it's your duration.
Id like to see what it would trap at the track as long
TECH Fanatic
Joined: Jan 2017
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When we talk durations we are also talking about valve events. A 240+ cam is way too big for a street driven 383 efi with hyd roller if you want it to drive nice and make lots of low end torque. This isn't a tuner problem it's a combo problem. Cam is too big for this application and the TB is known to have idle issues.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
What gets me is someone will say, "The cam's too big." And be mostly right.
Then someone comes along and says "My cam is bigger, and I have NO problem driving it!". As if to say, it's not being driven right, or not tuned right.
Truth is, some guys will put up with a ratty cam and feel it's OK. But it's still a ratty cam with poor street driving characteristics that tuning will only do so much with.
And so many of those ratty cams are there because of the sound, regardless of whether or not it's good for that engine combination. That just makes matters worse.
I've always erred on the side of, "when in doubt, under cam it a bit, and let a good set of heads do their thing"
OK, jumping off the soapbox now....
Then someone comes along and says "My cam is bigger, and I have NO problem driving it!". As if to say, it's not being driven right, or not tuned right.
Truth is, some guys will put up with a ratty cam and feel it's OK. But it's still a ratty cam with poor street driving characteristics that tuning will only do so much with.
And so many of those ratty cams are there because of the sound, regardless of whether or not it's good for that engine combination. That just makes matters worse.
I've always erred on the side of, "when in doubt, under cam it a bit, and let a good set of heads do their thing"
OK, jumping off the soapbox now....