3/S Head Swap

[mwinkle353]

Quote:

Originally Posted by c2xejk To me the truely interesting part is that despite putting down higher numbers on the dyne, my van was quicker on the street... Same dyne, same day so his car legitmately puts down more hp than my van. However, on the road, my van can walk away...

Yes, but what for torque did that other car have? I know for a fact that our motors hit darn near 90% of max torque as low as 2000 rpms. And that doesn't fall off until after 5000 rpms. You don't see many motors that can hold torque for as long as our motors do, straight from the factory (not to mention slightly modified).

[mightymulhern]

Quote:

Originally Posted by mwinkle353 Yes, but what for torque did that other car have? I know for a fact that our motors hit darn near 90% of max torque as low as 2000 rpms. And that doesn't fall off until after 5000 rpms. You don't see many motors that can hold torque for as long as our motors do, straight from the factory (not to mention slightly modified).

I think the gist is that the 12v setup puts down more torque earlier in the rpm band... but after about 4600 rpms, the 24v setup clearly has the edge. The plot below pretty much says it all. (this is SOHC-12 vs SOHC-24)

[c2xejk]

Some more aggressive cams and shortening the spacers would probably help the high-rpm hp... Before the spacers, the hp peak was higher in the RPM band.

I think to make higher RPM truely effective, the fuel curve needs changed...

[Shadow24V]

the 24v SOHC heads are good flowing heads stock, which is probably why they dont run out of steam until nearer to 6000rpms. they can be improved a lil though, probably better to P&P the intake mani and suchas though.

as for the van outrunning the eclipse, the eclipses are HEAVY, 3400-3600lbs. i dont know how much the van weighs though. the v6 is said to feel a lil weak for the size/weight of the eclipse.

About overrating motors, its an advertising gimik, most buyers dont know much about cars, so they wont necessarily feel or know that the car is slower than if it had the rated HP. donno if this was mentioned earier, but i think manufactures dyno motors sans accessories and transmission. once you add all that stuff, you dont get the advertized hp at all.

just my $.02

[Ondonti]

Quote:

Originally Posted by c2xejk He probably saw the claims of some the aftermarket reprograming tools that talk about big gains from reprogramming spark... Those claims are at best over hyped. They are likely going from the worst possible setup (ie worst case factory tolerance stack up) to the best. From what you are saying, he likely had already tweaked base spark advance, so an additional 5hp (whp?) is actually pretty good. It's funny, I know some pro's that would parts of there anatomy for even 3 honest hp.... Once you reach certain levels, more performance is tough to come by... I have spent hours on the flow bench looking for and trying to understand small gains in flow. And I know I will be spending even more hours pursueing even smaller gains... Time is money... The big gains in flow tend to come early. They are the low hanging fruit. Smaller gains come later and are much tougher to get... Dempsey was going after the smaller gains and he now has a tuning tool for when he makes other changes. But back to your comments, it sounds like the factory could push hp up by 9whp just by changing there spark curve...

I will say he was mad because he wasnt in a racing class where 5hp makes a huge difference. I think he probably bought the piggyback and was regretting it before he ever even got on the dyno.

But it should also be known he was only running 52mm TB and no porting of the plenum........that wasnt a modification people were doing then.
Maybe with a worked plenum he could squeak out a litttle more......Hard to tell now.

[Ntrain2k]

Hmmm....
Ported plenum..

Where did that come from? LOL!

[Ondonti]

Quote:

Originally Posted by Shadow24V the 24v SOHC heads are good flowing heads stock, which is probably why they dont run out of steam until nearer to 6000rpms. they can be improved a lil though, probably better to P&P the intake mani and suchas though. as for the van outrunning the eclipse, the eclipses are HEAVY, 3400-3600lbs. i dont know how much the van weighs though. the v6 is said to feel a lil weak for the size/weight of the eclipse. About overrating motors, its an advertising gimik, most buyers dont know much about cars, so they wont necessarily feel or know that the car is slower than if it had the rated HP. donno if this was mentioned earier, but i think manufactures dyno motors sans accessories and transmission. once you add all that stuff, you dont get the advertized hp at all. just my $.02

I think you are getting ahead of yourself
3rd Gen eclipse are like 3050# or so in the early years
This is the car we are talking about and that was dyno tested
NOT the........
4th gen eclipse.........THOSe are lke 3500+# depending on engine package etc.

[Shadow24V]

woops lol, knockout cold medicine + posting = jibberish

ok, maybe the 3g isnt THAT heavy, but a roadster in isnt lol

[c2xejk]

But I would guess that my Voyager is heavier... Less aerodynamic too...

[m90daytona]

Quote:

Originally Posted by m90daytona so what all was done to the heads on the van? did you flow bench them? what where the results?

????????????????

[c2xejk]

Lots of epoxy on the intake ports. Some welding on the exhaust ports. multi-angle valve job with the stock valves back-cut.

I don't have my log book handy, but flow was clsoe to what Brent got from the his big valve ports...

[mwinkle353]

Just imagine if you were to run big valve and a reworked head like yours.

[Ondonti]

Well if he is getting 200+ cfm's @ .400" lift then I feel sorry for the TD guys who diss 3.0 heads.

[c2xejk]

Next up for me is a set of heads for Stein. I havn't made the final decision on valve sizing, but I am leaning toward +1mm Intake and +4mm Exhaust...

Right now I am reworking my flow bench to hopefully make it easier, quicker and more accurate.

I think there is much potential in the 3L heads... I think I could do better yet with even the stock valves...

[m90daytona]

do you plan on selling these?