Kinda intrigued by the 1 5/8ths to 1 3/4 design for lower end torque. Any body have them or do you think it will help with bottom end?

 

The only way they're any better for low end torque
than any other header, is for them to be a much
longer primary tube. Which would be rather surprising
given the envelope constraints.

My opinion of Hedman, is they're just cheap and that's
all they have going for them.

 

Yes they help low and midrange power. I was somewhat disappointed when switching to a 1 3/4 header that I lost so much midrange and throttle response. You can't tell some people because they believe what they want to, sometimes you just have to experience it. These were on my car when i bought it.

 

I have seen two cars around here with them. Both cars ran well with them while they were bolt on only cars. But once you go cammed, they are lacking compared to normal 1 3/4 headers. Both cars picked up et and mph on the track, and one showed horsepower and tq differences on the dyno. I cant remember the numbers, its been about 5 or 6 years ago.

 

I had a set and a matching ory, just sold them for a set of tsp 1 7/8's also doing a custom ory but they were great headers tucked decent, good fitment, the ory sucked crappy merge fitment was ok!!!

 

From the dyno results, fitment, and quality of product I've seen I would be looking no further than TSP 1 7/8" stainless.

2 of my local friends have them and they are extremely nice

 

Its gonna be a while before I do any cam or head work. Wouldn't the 1 7/8 hurt low end on a stock motor? I have to put a rear end under the car before the cam and I have to get a hood and front bumper painted first. I want something to help with the lag between 1500 & 3000 range

 

Curious what you mean by lag.

 

It's not really lag but the torque on the low end is nothing compared to the higher rpm's.

Here is the 0-60mph. You can see and feel there is way more torque from 3000 rpm up. I just don't think there is enough on the low end.

https://ls1tech.com/forums/pontiac-f...ifference.html

Not talking about when the tcs kicked in either.

 

That is just really the nature of the lsx platform. My bone stock 5.3 is the same way. The engines just run so much better up top it makes it feel like they are lacking down low.

You will often hear people claim a lt1 has more low end than a ls1. That is why. If you dyno the 2 cars in question you will not find a lot more tq on the lt1 graph (if any).

If you mod in a way to reduce that illusion/feeling I would be worried that you are doing mods that benefit the low end but do not help top end at all. You might be ok with that, but to me that sounds like lost potential. Makes me think of an 80s big block, tons of torque but sub 200 horsepower on a platform that you have to try not to make 400hp.

 

I know I have a "torque adjustment" in my right foot but I would rather try to help the engine with a little more low end torque.

 

The lack of lowend torque of LSx motors is a myth. The attached dyno sheet is from after the can was installed in my car, but if anything an aftermarket cam woulld be detrimental to low end torque unless specced to that purpose. Above 300 tq from 2400 rpm.

 

Well their price isn't that cheap and they do have a lifetime warranty. Just sayin'

 

Dynos usually start at 3k. When people say motors have a lot of torque they aren't referring to 3k. Typically engines feel really strong if they have power available around 1k to 1500 rpms. Lt1s are most definitely a more torque oriented motor, though a 3k and up dyno really may not show it.

 

Very true. But I seem to recall someone posting up a graph on this forum of a pull starting much lower in a manual car for the sake of testing the idea. I will try to find it when I get a chance.

I still retain my original argument though. While the 5.3 in my truck has excellent response off idle, it still feels like it really starts to get wound up around 3k rpm and up just like every other lsx type engine I've driven. It is stock except for a drop in filter, not even a muffler on it yet.


EDIT: Found an old archive post but no picture

Injuneer 01-02-2005 07:23 AM
The limited data quoted in the original post simply tells you the LS1 makes more torque at peak.... it doesn't tell you anything about low end torque. The Torque vs. RPM lines are not "straight".

I have a Corvette fuel injection manual covering the 91 L98, 92 LT1, and 97 LS1. It includes a small graph showing the torque curve for each engine. If you think about it, the Corvette factory numbers are probably more accurate indicators of each engine's actual performance, since the F-Body numbers were probably artificially reduced to keep it from looking like a better bargain than the Corvette:

L98: 340 lb-ft @ 3,200rpm
LT1: 330 lb-ft @ 4,000rpm
LS1: 350 lb-ft @ 4,400rpm

Looking at the torque curves, up to 2,000rpm the LS1 and LT1 are virtually identical. The L98 is only the width of the printed line lower than the other two engines.

At 2,000rpm the LT1 and L98 cross, and the L98 continues to climb while the LT1 torque curve actually lays over and starts to decrease slightly, until it levels out at 2,800rpm. At the same time, the LS1 curve is continuing to climb, and showing a greater torque than either the L98 or LT1. I would estimate the curve shows the LS1 is making about 25-30lb-ft more than the LT1 from 2,500-3,000rpm.

At 3,200rpm, the L98 lays over and torque drops rapidly. By 4,000rpm is is back down to maybe 220 lb-ft. The LS1 continues to maintain its significant torque edge over the LT1 all the way to redline. I'd say from 4,500 to 5,000rpm the LS1 is up by about 40 lb-ft.

Point is, the LS1 - at least the C5 version compared to the C4 LT1 - DOES NOT AT ANY POINT PRODUCE ANY LESS TORQUE THAN THE LT1. The idea that the LS1 has a "weak bottom end" would appear to be pure urban legend.... perhaps fueled by the feeling that the LS1 torque continues to build while the LT1 sort of peters out. The LS1's extremely strong top end makes it feel weaker on the bottom end, but the published data would appear to show that it isn't.

 

I understand raw numbers don't lie. However when people speak of torque its a feeling. An engine with longer intake runners, lower rpm torque converter, lower cfm heads and other intake track related items, smaller exhaust primaries all contribute to an engine that feels stronger on the bottom end. The original 5.0 was a very torque oriented engine though we all know that even with H/C/I they struggled to break 225 whp. The cars were light-weight and the intake runners were long, making throttle response off idle really good and making it feel like the engines didn't have to work hard at all to get the cars moving. Again, if you barely blip the throttle and the front end wants to lift and unload the suspension it makes the car feel very torque oriented. That is just not something a dyno can/will show. LS engines don't feel this way for several reasons, two main things being higher stock converters and a general higher powerband. I used to have a 305 TPI in a 3rd gen and it felt very strong in the low to midrange, very responsive and eager, but the reality was it was a 15 second car.

 

I think we are both coming at the same point just from different sides. haha

I agree with you that torque is a big part of driving feel. I read your posts as commentary on the impact of off idle/low end response and it's impressions on the driver.

I'm coming from the other side talking about how that feeling can be confused by the top end pull that is natural to the lsx design and the way the combo is setup (both from the factory and after modding is done).

So back on topic to the OP, I think we would both agree if he wants that low end punch there are ways to help get some more but the sacrifice is the gains which could be had where the ls1 already shines up top.

If improving low end is the goal, the headers in question sound like they will give the desired result, but by using them he will be missing the opportunity for top end gains of a more conventional longtube design in either 1 3/4" or 1 7/8". Of course this is preference and there is no right/wrong answer.