et gain's with heads ....
et gain's with heads .... I'm looking for some real world et gain's (before and after) with cylinder head's on an ls1. Iv seen dyno numbers to no end so I'm not looking for that, iv found vary little feed back from people who have done it. I would assume if there positive gain's I'd hear more about it. Iv done many cam and h/c combo's for other people in the past but never one then the other, seems the h/c combo's don't do any better then cam only. I know there's 15-20 HP and 20-30 lb torque to be had with a ls6 head swap but is 1k dollar port job worth it? Let's say PRC or AI ported head or even aftermarket for that matter I'd like to hear some honest feedback.
I know there's a lot of variables but I'd like to hear your combo and what you picked up. Thanks
I know there's a lot of variables but I'd like to hear your combo and what you picked up. Thanks
seems the h/c combo's don't do any better then cam only.
Heads are one of the better mods to do, as it increases power, torque and efficiency everywhere in the power band...from idle to redline. Can't say the same about many other mods specially not cams which have a specific range where they perform well.
My car went from a Comp 230/224 XE lobed cam and stock heads to an EPS 230/238 cam and some 799s with minor hand porting on the intake runner only and milled .010"
ET went from 12.24 best to 11.67 best
MPH went from 111 mph best to 116 mph best (on 2 passes) but a consistent 114-115
Not sure where you see heads/cam cars not going faster than cam only unless you are comparing max effort cam only cars to heads/cam street/strip cars. The bulk of cam only full weight street cars are going to be low 12s to high 11s. The bulk of similar heads/cam cars should be in the low-mid 11s.
Another real world example is I was at a dyno day with 2 98 ls1 manual cars both tuned by me, both using ls1 intakes and longtubes. The stock head car made 330rwhp. The other car had .030" milled 799s (stock ports) and made 349rwhp.
I would not swap stock 243/799 onto a car. Too much money and work for the HP gains which most of the time I think will be in the 15rwhp range.
ET went from 12.24 best to 11.67 best
MPH went from 111 mph best to 116 mph best (on 2 passes) but a consistent 114-115
Not sure where you see heads/cam cars not going faster than cam only unless you are comparing max effort cam only cars to heads/cam street/strip cars. The bulk of cam only full weight street cars are going to be low 12s to high 11s. The bulk of similar heads/cam cars should be in the low-mid 11s.
Another real world example is I was at a dyno day with 2 98 ls1 manual cars both tuned by me, both using ls1 intakes and longtubes. The stock head car made 330rwhp. The other car had .030" milled 799s (stock ports) and made 349rwhp.
I would not swap stock 243/799 onto a car. Too much money and work for the HP gains which most of the time I think will be in the 15rwhp range.
Et at the track, watching IDC and maf in the tune I can tell they move air above 6k rpm so I know the power shows up on a dyno, but most people bump cr way up when they do the head's and I'm wondering if most the power just comes from chamber and not the runner porting. I'm not ruleing it out I'd just like to see real proff.
My car is cam only and I have set of 243s iv been wanting to put on, how much faster will it be if had the runners ported? (That's a loaded question but you know what I mean).
As far as h/c cars vs cam only, there's just no good proff for me cause each car iv done has different Bolton's, converter, gear etc... So it's hard to say.
My car is cam only and I have set of 243s iv been wanting to put on, how much faster will it be if had the runners ported? (That's a loaded question but you know what I mean).
As far as h/c cars vs cam only, there's just no good proff for me cause each car iv done has different Bolton's, converter, gear etc... So it's hard to say.
My stock heads were milled about the same BTW, I pulled the 98 heads off my engine in favor of stock 99 heads for the centerbolt covers
IDC cam only was hitting high 90s to like 101% at redline. After the heads IDC was hitting 110% by 4500rpm so I had to install larger injectors before I would even rev over that.
Here are mine, notice the rocker bolt boss has been removed, swirl ramp removed, trimmed the valve stem boss, and sanding rolls to remove flash...no shaping was done the the walls or port openings. The exhaust side got nothing but sanding. Stock valve job on all seats/valves, just hand lapped them in before install:
IDC cam only was hitting high 90s to like 101% at redline. After the heads IDC was hitting 110% by 4500rpm so I had to install larger injectors before I would even rev over that.
Here are mine, notice the rocker bolt boss has been removed, swirl ramp removed, trimmed the valve stem boss, and sanding rolls to remove flash...no shaping was done the the walls or port openings. The exhaust side got nothing but sanding. Stock valve job on all seats/valves, just hand lapped them in before install:
It could just be something in the combo or the rest of the car that caused them not to run better, the factory runner has a swirl ramp and a cast runner which help's mix the air and fuel better, idk just kind of wanted more hard proff before sending them in for porting. My butt meter say's they just move the power curve higher and cause's a need for shorter gears and bigger converters.
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Verdad Gallardo A 3600 stall hides a lot, but on the first drive it was very apparent how much was gained down low. The most impressive gains to me weren't even in the top end, it was the way the car "hit" right off idle on small amounts of tip in throttle response.
That's not to say the top end pull didn't become violent...it was revving so fast it wanted to keep pulling past the 5000 rpm rev limit I had set.
I used the white Bosch injectors from supercharged 3800 v6 GM cars. They are 41.5# at ls1 fuel pressure and you can buy them for $80-100. I bought a set on ebay for around $60 before they got more popular.
That's not to say the top end pull didn't become violent...it was revving so fast it wanted to keep pulling past the 5000 rpm rev limit I had set.
I used the white Bosch injectors from supercharged 3800 v6 GM cars. They are 41.5# at ls1 fuel pressure and you can buy them for $80-100. I bought a set on ebay for around $60 before they got more popular.
Heads are arguably the most important part in the hp equation. People fixate on cam which affects when power happens and fixate on displacement because "mine is bigger than yours" sounds good but heads are where all the flow coming and going happens.
Couldn't agree more. Heads will be the last thing I do on my set up. I wish it was the first thing I did. My car is like a sleeping dog on the dyno lol. Can't wait to wake that bitch up one day with some AI ported heads.
I completly agree with you guys, but the head's work so well stock I just dont think there's that much left to gain, I'm basically asking to be proved wrong but i like to have hard proff, real et gains not just more HP on a dyno. Every company I call about head's go's off on dyno numbers and that's all they have. More peak HP don't mean you will go faster. Bigger ci engine or with a cam/intake setup to pull to 7500+ you will clearly see a gain with ported runners. Like said above a 243 head cleaned up a little does a lot. Air speed is just as important and cfm.
I completly agree with you guys, but the head's work so well stock I just dont think there's that much left to gain, I'm basically asking to be proved wrong but i like to have hard proff, real et gains not just more HP on a dyno. Every company I call about head's go's off on dyno numbers and that's all they have. More peak HP don't mean you will go faster. Bigger ci engine or with a cam/intake setup to pull to 7500+ you will clearly see a gain with ported runners. Like said above a 243 head cleaned up a little does a lot. Air speed is just as important and cfm.
Look at the mods in my sig. My numbers suck when compared to what I've spent. All because my heads suck when compared to the supporting mods. Unfortunately, my last mod will most likely be the most expensive
I have, not trying to make an argument here I'm just stating what iv seen. I understand every combo will be different as well, I'm just curious on your average fbody if you swap out ported heads will you see it on the track, I did a car just like mine nearly the same cam and all only difference was CNC and milled 243 heads and he had a ss4k converter vs my 3400 and he can't beat mine mph or et. All I get is speculation and dyno numbers that's why I'm asking if anyone has done a before and to compare et.
Tune? Weight? Mechanical problem brewing?
Are his heads actually good? LOTS of shops out there get paid to do mediocre at best work. I am not asking you to name the shop.
There are a lot of shops who have great reputations and few results to back it up, all salesmanship no skill.
I have hurt some feelings showing up same day same track walking stroker cars because I spend money on truly good heads rather than displacement. Of course the whole package has to work but heads are the foundation of HP.
Are his heads actually good? LOTS of shops out there get paid to do mediocre at best work. I am not asking you to name the shop.
There are a lot of shops who have great reputations and few results to back it up, all salesmanship no skill.
I have hurt some feelings showing up same day same track walking stroker cars because I spend money on truly good heads rather than displacement. Of course the whole package has to work but heads are the foundation of HP.
I did a car just like mine nearly the same cam and all only difference was CNC and milled 243 heads and he had a ss4k converter vs my 3400 and he can't beat mine mph or et
More peak HP don't mean you will go faster
but the head's work so well stock I just dont think there's that much left to gain,
Last edited by redtan; Dec 9, 2014 at 08:51 AM.
Yes but most companies do ALL there testing on a dyno or flow bench and frankly 90 percent of costumers are completely happy if there car make's more power when it gets dyno tuned. I'm not going against the idea that they can run faster I just would like to see some combo's were it's been proven on the track.
Dude, all the dyno is for is tuning and comparing before and after gains. As for the track, there are so many things that can effect et...Say you ran a 12.6 before heads and 12.8 after. The shitty time can be due to not having the suspension and tires set up for the added power.