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If you look at the blue line, that was the original build 1 5/8" headers, no x-pipe, cats, No Fast 92 intake, 78MM MAF and LS1 Throttle body. The red is the base line run after mods. With the original build, I had more torque much sooner and more horsepower on the low end all the way up to almost 5000rpm's. Where did all that go, lol. Is it the 1 7/8" headers, the 85mm MAF, the ported FAST 92, the ported throttle body or is it the cam? Where did the low end go?? Don't get me wrong I think the final HP number of 477 is good, but it seems like it comes on from 4500 to 6800 RPMS. I am missing the low end. Is there anything, beyond gears that I can do? Thanks
Sorry if I missed it, but what heads are on the car? My LS1 is right at 470RW with heads and a 228R cam, long tube headers. Stock intake, injectors, fuel pump, throttle body and bottom end.
If you look at the blue line, that was the original build 1 5/8" headers, no x-pipe, cats, No Fast 92 intake, 78MM MAF and LS1 Throttle body. The red is the base line run after mods. With the original build, I had more torque much sooner and more horsepower on the low end all the way up to almost 5000rpm's. Where did all that go, lol. Is it the 1 7/8" headers, the 85mm MAF, the ported FAST 92, the ported throttle body or is it the cam? Where did the low end go?? Don't get me wrong I think the final HP number of 477 is good, but it seems like it comes on from 4500 to 6800 RPMS. I am missing the low end. Is there anything, beyond gears that I can do? Thanks
You added all those mods and lost power, your car is hanging (explain "hanging"?) like it's surging?
One thing you know is something isn't right. Mechanical parts swaps are easy and can be done innyour own garage. I would start there. It's not throwing any codes?
Sorry if I missed it, but what heads are on the car? My LS1 is right at 470RW with heads and a 228R cam, long tube headers. Stock intake, injectors, fuel pump, throttle body and bottom end.
I think he's low on power as well. But not knowing which heads he has he could be leaving power on the table there.
None the less an LS1 383 stroker with 477whp will whoop the daylights out of a peaky 470whp H/C/I LS1. The major benefit to a 383 stroker is torque under the curve. Similar power at the top but much different animals down low.
LOL... I'm going to try to explain this. There are a few dyno graphs so it might be confusing. The chart below, in blue you will so the original build at 417RWHP and 418 torque. What you're seeing below in red is after all the parts Fast/LS2/MAF/Bigger Headers, that was 460RWHP with 406 Torque, again the base line tune and then it was tuned from there and we got 477RWHP and 435 Torque. I was saying I lost both low end HP and Torque.
I talked for a while with a gentleman at Texas Speed (super helpful by the way). He said that is what will happen when you go up in cam size, generally you lose some on the lower and gain both HP and torque in the upper RPMS. He thought HP was right for the build, he said we could go with different heads and get right at 500hp.
Sorry I don't have a dyno graph that compares the Old Tuned build against the new tuned build. Hope this helps.
These are stage 2 factory GM heads. Like I said the car was built in 2000 with a few 100 miles on it. So I am sure head technology has come along way. Stage 2 would be stage 2 port and valves. The gentleman at Texas Speed thought some heads would bring it right at 500hp.
What I mean by "hanging" is when driving in second gear on up if I press in the clutch and let of the gas the RPM will stay at 1500-2000. In second gear on up if im driving and just let off the gas it is like the cruise control is set at 2000rpm it just maintains that speed. When I come to a stoplight it will drop to idle after a bit? Hope this makes sense,
I attached a pic of the head for you. Thanks for all the help guys. Casting number is milled off, I'm assuming when the head work was done.
LOL... I'm going to try to explain this. There are a few dyno graphs so it might be confusing. The chart below, in blue you will so the original build at 417RWHP and 418 torque. What you're seeing blue is after all the parts Fast/LS2/MAF/Bigger Headers, that was 460RWHP with 406 Torque, again the base line tune and then it was tuned from there and we got 477RWHP and 435 Torque. I was saying I lost both low end HP and Torque. I talked for a while with a gentleman at Texas Speed (super helpful by the way). He said that is what will happen when you go up in cam size, generally you lose some on the lower and gain both HP and torque in the upper RPMS. He thought HP was right for the build, he said we could go with different heads and get right at 500hp.
Sorry I don't have a dyno graph that compares the Old Tuned build against the new tuned build. Hope this helps.
Gotcha. This is why some of us above were recommending a gear swap with that cam. You'll make up for that lag at the bottom with the gears.
At the moment I would be more concerned with the "hanging" than the dyno results. If it's not running right it could be part of the reason for the power drop. If there is an issue gears won't fix that.
Did Texas Speed have any feedback on the car "hanging" on you?
These are stage 2 factory GM heads. Like I said the car was built in 2000 with a few 100 miles on it. So I am sure head technology has come along way. Stage 2 would be stage 2 port and valves. The gentleman at Texas Speed thought some heads would bring it right at 500hp.
What I mean by "hanging" is when driving in second gear on up if I press in the clutch and let of the gas the RPM will stay at 1500-2000. In second gear on up if im driving and just let off the gas it is like the cruise control is set at 2000rpm it just maintains that speed. When I come to a stoplight it will drop to idle after a bit? Hope this makes sense,
I attached a pic of the head for you. Thanks for all the help guys. Casting number is milled off, I'm assuming when the head work was done.
Sorry, trying to multitask and not keeping up well with your posts. Sounds like your tune is still off. If it were a vaccum leak (which Fast intakes have had issues with) or your throttle body it would likely be throwing codes.
T/S had a few ideas....
1) Tuning... I don' think that I had 2 really good tuners dyno and street tune the car. They couldn't figure it out, comes and goes not constant
2) Vacuum leak, possibly PVC?
3) Ported Throttle body? I have another ported LS2 coming that I will swap it with and see if that takes care of it.
4) Fast 92 Intake Leak? Possible I guess? Not sure?
T/S had a few ideas....
1) Tuning... I don' think that I had 2 really good tuners dyno and street tune the car. They couldn't figure it out, comes and goes not constant
2) Vacuum leak, possibly PVC?
3) Ported Throttle body? I have another ported LS2 coming that I will swap it with and see if that takes care of it.
4) Fast 92 Intake Leak? Possible I guess? Not sure?
That's the ideas thus far?
Both tuners had the same issue. So either they are missing something when tuning idle, RAF etc.. Which is possible but you said they are both "good". So that points to your ported throttle body.
Ported TBs when just installed without a tune will do what you described. A proper tune usually corrects this.
You'll know pretty quickly, once you swap the TB, which one was off...the tunes or the first ported TB. If it's the tune...fire the two other guys...and find the right guy.
Make sure it's a proper tuner from a reputable Speed shop and not a friend with a hobby that seems to know his stuff.
If you look at the blue line, that was the original build 1 5/8" headers, no x-pipe, cats, No Fast 92 intake, 78MM MAF and LS1 Throttle body. The red is the base line run after mods. With the original build, I had more torque much sooner and more horsepower on the low end all the way up to almost 5000rpm's. Where did all that go, lol. Is it the 1 7/8" headers, the 85mm MAF, the ported FAST 92, the ported throttle body or is it the cam? Where did the low end go?? Don't get me wrong I think the final HP number of 477 is good, but it seems like it comes on from 4500 to 6800 RPMS. I am missing the low end. Is there anything, beyond gears that I can do? Thanks
Cam is too big. Low end torque loss with
gain in power at higher rpm’s is typical.
Steeper gears to get into the power band quicker is a band aid solution.
Looking at your dyno plots, your car should have felt a lot stronger with the original setup
during normal driving.
It did feel stronger just driving around town. The new set up feels much stronger from 4 to 6500. So if I'm rolling at 4000 in second gear shift at 6500ish into 3rd it'll drop to 4000 and I stay in that power band. If I raced old set up at a rolling 4000, the new set up would kill it.
Drove the car a bunch today. It's different... not worse just different. Had fun in the car today.
That’s a pretty big cam. So the lost low end is to be expected. I agree with the others that the hanging issue sounds like a tuning problem. I also agree with texas speed, your cam is big enough that you could squeeze out another 20-30 horsepower with better heads
I don’t know what stage 1 or stage 2 heads from the factory are, but the Z06 (243) were the best they had at the time, and they did not arrive until 2001. My guess is your heads, in general, are not a good match for all the other upgrades.
Without the car in hand, we’re speculating, but would agree with others that the cam is too much and the heads, not the headers, are the choke point. This has nothing to do with your hanging rpm issue, BTW.
Putting the rpm thingy aside, the cam and heads need to be of the same power making potential. I’d bet you’d like better heads, than a smaller cam. Just a guess …. From a practical standpoint, better heads will support all your other mods, so you’ll be going forward with your build, and not throwing out good components.
Along with head-cam solution, some lower gears are in order to hit the rpm’s that will get the cam in its power band. OMG will that be a wild ride! I’ve had 3.90s behind a stock motor, and it flat woke that car up. Freeways are no problem with that serious OD ratio in 6th. In fact, the 3.90 or 4.10s actually are very nice around town and in general as they seem to match up well with the trans gearing for typically posted speeds. They should have come from the factory that way, that’s how well they drive.
Good luck finding your gremlin! Sometimes you just have to spend your way out of it…
Hypothetical question??? If I would have left the other CAM in and still did all the other Mods (Ported Fast 92, Ported LS2, 1 7/8" Headers and X-Pipe) how much of an increase would I have seen? Original before mods was 417rwhp and 418 torque. I am trying to figure out if I should just throw the other cam back in? Thanks
Hypothetical question??? If I would have left the other CAM in and still did all the other Mods (Ported Fast 92, Ported LS2, 1 7/8" Headers and X-Pipe) how much of an increase would I have seen? Original before mods was 417rwhp and 418 torque. I am trying to figure out if I should just throw the other cam back in? Thanks
The previous results spoke for themselves. On the other hand, the upgrades for the big cam would not hurt the performance of the old cam. There might be a more responsive throttle, and there may be some benefits at higher rpm’s.
From a cash standpoint, sticking the previous cam back in would be beneficial. And, if you find yourself with a few grand burning a hole in your pocket at some point, you can get some nice heads and reinstall the big bump stick.
Thanks for the reply. I've got the money so if sticking with this set up an putting better heads on this combo will add me some HP and low end I'm in. Texas Speed, with a new set of heads thought I could get to 500 pretty easy. Would I gain back some of the low end???
Or do I just stick my old cam back in and hope for 440ish?
Like I said I have the money and can go either way. That said, I want a car that is not a pain in the *** to drive on the street. This car will never see the track or drag strip. At most I take it out for a drive on Friday night for an hour and see if I can find any Dodges, STI, EVOS, Supras and so on. If I do great, if not I just enjoy the drive. Hope this helps.
I'm thinking, move forward not backward. Go with better heads and see where that takes you. I agree that you will probably want to go with a 3:90/4:10 at some point.
Of course, with the new heads, you'll need some more tuning, and perhaps the hanging issue will reveal itself there, or maybe go away with the better heads.
Texas Speed has decent heads but Tony Mamo sells the end all be all in terms of heads. Aftermarket castings tend to make more under the curve than a ported factory casting. Even a non-ported TFS or AFR casting will be money better spent than porting any factory casting. That paired with a cam with a tighter LSA and some advance ground into it will give you a shift in power where you want it, plus more overall.
I agree with everything everyone is saying and thanks for all the help. Here is where I am at. The car made 417rwhp and 418 Torque without Ported Fast 92, Ports LS2, Headers, Xpipe, and the new cam. So I added all that and a few other things (APR Dampner, Hardened Pushrods, Belts and hoses) at a cost of approx. $6000 with install. That got me to 477rwhp and 435 torque. If I go with Mamo heads, I am looking at I would guess another $4000 to get to 500rwhp ish? So now were in $10,000 ish.
Just trying to digest all this, not sure if the 30hp is worth another $4000 to me? If I got back my low end and the car drove nice around town, I think I would be in for that. But the more research I do, it seems like there is going to be a definite sacrifice in street drivability with a 500rwhp N/A car. There is a pretty lengthy thread about it, I will try to find it.
I would rather have 450rwhp that drove great around town, then 500hp that bucks around parking lots, lol. I am sure I am not the only one that's been here? Thoughts
08-05-2022, 04:28 PM
…. From a practical standpoint, better heads will support all your other mods, so you’ll be going forward with your build, and not throwing out good components.
