370 build need help on picking heads
If you want to maximum performance the short answer is yes. Change the cam. Have one spec'd for what your doing. If you end up wanting more lope you can tune some more into it at idle using the timing trick. Don't end up with something that runs like **** but sounds good at idle.
Sell the current cam to recoup some cash towards a new one.
Sell the current cam to recoup some cash towards a new one.
823 heads make more torque......similar build Got torque? 370/AI/LS3 intake/4L60E
Most people telling you to use 799 heads are just quoting what they read on the Internet.
Most people telling you to use 799 heads are just quoting what they read on the Internet.
All you're doing is just quoting what you have read on the internet...
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From: Mississippi
The cam I mentioned in the first post I made here in this thread would be a great choice!!
DUR @ .004" 272*/280*
DUR @ .050" 210*/218*
LIFT .551/.551
LSA 116*
That cam with L92 heads make over 460 Ft Lbs of torque and over 460 horses to boot!! Go any bigger that this cam here and you'll lose torque down low. I'm like Hiss that cam you have now is way to big for a truck that's go see mud holes. Your motor will hardly ever see 6k so why do a cam that starts to generate power at 3500 rpm instead of doing a smaller cam that starts to hump hard at 1500 rpm.....
If you want a choppy idle just get the the cam on lower lobe separation angle....
Good luck brother.
DUR @ .004" 272*/280*
DUR @ .050" 210*/218*
LIFT .551/.551
LSA 116*
That cam with L92 heads make over 460 Ft Lbs of torque and over 460 horses to boot!! Go any bigger that this cam here and you'll lose torque down low. I'm like Hiss that cam you have now is way to big for a truck that's go see mud holes. Your motor will hardly ever see 6k so why do a cam that starts to generate power at 3500 rpm instead of doing a smaller cam that starts to hump hard at 1500 rpm.....
If you want a choppy idle just get the the cam on lower lobe separation angle....
Good luck brother.
Thread Starter
Teching In
Joined: Oct 2013
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How much would I benefit from trying to get the compression up to 11:1 with the l92 heads? I dont mind milling if I have to and I'm still trying to decide on what pistons to run to maybe get the compression up but I know those valves are so big that you have to watch ptv clearance.
More compression is always good, especially on low end torque.
You shouldn't worry about PTV. First of all your cam selection should leave you with plenty of clearance. Secondly, most if not all aftermarket forged pistons come with some sort of valve reliefs built in so even if a cam would have clearance issues with a true flat top, the valve reliefs would more than offset that.
If you truly have PTV issues with slightly milled heads and valve reliefs then you have chosen a humongous cam which would be counterintuative for what you're doing.
You shouldn't worry about PTV. First of all your cam selection should leave you with plenty of clearance. Secondly, most if not all aftermarket forged pistons come with some sort of valve reliefs built in so even if a cam would have clearance issues with a true flat top, the valve reliefs would more than offset that.
If you truly have PTV issues with slightly milled heads and valve reliefs then you have chosen a humongous cam which would be counterintuative for what you're doing.
Exactly to prove a point. Its easy to pull **** up on the Internet when you have no real world build experience. Do you have any real world experience with square ports or are you just trying to keep the prices up on cathedral stuff like everyone else preaching it.
To the OP. I think the cam suggested was a bit on the smallish side. I also think more split in duration would net better results. I'm not a cam grinder, nor do I pretend to know what the perfect camshaft would be for your specific engine. I suggest you give Martin Smallwood, Ed Curtis, Pat G or someone who does that for a living a call. I don't think you can go wrong with any of them. As for the cathedral vs square debate......let's take the port shape out of the equation. Would you prefer to have a set of heads that are flowing over 310-330 depending on the bench cfm out of the box, or a set that are flowing 250-260 cfm?
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Would you prefer to have a set of heads that are flowing over 310-330 depending on the bench cfm out of the box, or a set that are flowing 250-260 cfm?
Yes, let's focus solely on Flowbench numbers. Everyone knows you can't go wrong comparing only Flowbench numbers...
Thread Starter
Teching In
Joined: Oct 2013
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I really like the long flat torque curve from the example "got torque" that HISS showed. I feel like for what I'm doing that would do well. I think I'm gonna replicate that. it makes 400 ft lbs by 3400. That should be good.
Fact: I have personally seen square port headed 370 inch motors make more average, and more peak on a load bearing chassis dyno. Hard to argue when the two local shops are building these cars and the same people are putting together cam specs. Have I seen cathedrals make more or equal power, yes. Have I seen stock 799's make more power than square ports.....the fact yall are even arguing this is laughable.
^truth^. Also in stock form.
To the OP do whatever smokes your tennis shoes, I guarantee those 823 heads will make more avg and peak than a set of cathedrals of any stock casting number will. Especially with one of the good camshaft gurus recommending a camshaft for your operating range.
If you decide on cathedrals good luck with the build also.
To the OP do whatever smokes your tennis shoes, I guarantee those 823 heads will make more avg and peak than a set of cathedrals of any stock casting number will. Especially with one of the good camshaft gurus recommending a camshaft for your operating range.
If you decide on cathedrals good luck with the build also.
Last edited by HISS; Mar 20, 2015 at 04:34 PM.
Fact: I have personally seen ... Hard to argue when the two local shops are building these cars.
The other hundred upon hundred of performance/speed shops in the country are all wrong, everything that you have known about heads is irrelevant, all the records and results of the past 2 decades don't matter. These 2 holy grail of shops have re-written the book on making power in the internal combustion engine and nothing else matters.
Last edited by redtan; Mar 20, 2015 at 05:26 PM.
That's it guys. Because HISS himself has seen a few builds done by 2 shops in the country means this is it, the end, no more arguments, case closed, finito.
The other hundred upon hundred of performance/speed shops in the country are all wrong, everything that you have known about heads is irrelevant, all the records and results of the past 2 decades don't matter. These 2 holy grail of shops have re-written the book on making power in the internal combustion engine and nothing else matters.
The other hundred upon hundred of performance/speed shops in the country are all wrong, everything that you have known about heads is irrelevant, all the records and results of the past 2 decades don't matter. These 2 holy grail of shops have re-written the book on making power in the internal combustion engine and nothing else matters.
I am in the process of getting all my parts together for a 370 build. I have a 03 lq4 block getting bored .030 over. I am running stock crank but aftermarket rods and pistons. I got a good deal on a spinmonster 230/234 .613 .598 lift 114+2 cam and dual valve springs. I have a good set of untouched 799 cathedral port heads and untouched 823 rectangle port heads. I have a rectangle port truck intake but am not against getting something different. I haven't ordered pistons yet, was trying to figure out which heads I was gonna use. This is going in a s10 4x4 street mud truck. Which heads would best suit my needs? I want to make the best power possible but also broad torque curve. Is 500 fwhp possible from one of these combos?" Maybe you should actually read that again......500 whp from 799's on a 370 inch engine wont freaking happen period, 823's are a better option. The OP has access to both.
The point I was making is I'm not making an assumption based on the opinions YOU have read on the Internet. If you are still arguing the fact that stocks 799's make more peak and avg horsepower than 823 castings you are ******* dumb. I'm done arguing with you, I'm trying to help the op make his power goal, not getting into a dick measuring contest with another "well I read it on tha intraweb so it must be true." To the OP if you have any questions I can help answer just shoot me a PM.
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From: Wilmington, De
I'm a huge proponent of the rectangle port heads, and I actually have a set of LS3s on my 404.
However, I do not think those heads are a good choice for a 370. Since milling will be required to achieve compression, chamber size is irrelevant, but runner volume and design isn't, and the larger rectangle ports are going to naturally move the power band up in the motor. The "Got Torque" example that was posted does not show a good example for something that is going to be used for mudding. That torque curve is horrendous before 3500 RPMs and is nowhere near what I would define as "flat." You want something that builds decent torque at 2000 RPMs and keeps the curve flat throughout the range.
The following is a graph of a 383 TPI engine. Don't concern yourself with the numbers. Just look at the curves. This is what a flat torque curve looks like:
However, I do not think those heads are a good choice for a 370. Since milling will be required to achieve compression, chamber size is irrelevant, but runner volume and design isn't, and the larger rectangle ports are going to naturally move the power band up in the motor. The "Got Torque" example that was posted does not show a good example for something that is going to be used for mudding. That torque curve is horrendous before 3500 RPMs and is nowhere near what I would define as "flat." You want something that builds decent torque at 2000 RPMs and keeps the curve flat throughout the range.
The following is a graph of a 383 TPI engine. Don't concern yourself with the numbers. Just look at the curves. This is what a flat torque curve looks like: