20v building na

[The Real Roadrunner]

So 1.1mm difference in lift, duration should still be the same but the ramp angles would be a little tamer with a 20v.

have you measured the port vs valve area between the 2? 20v should be heaps better in that department and you can modify the cam grind to change the shrouding affects slightly.

ill chat with Abe and find out the cam specs in the big 20v we did, im pretty sure they are over 10m but not by much.

cheers
linden

[old_school_jap1]

Is that 185 rwhp you built mate ?
Care to share the specs bottom end and head specs ?

Cheers

you can find it all on his site; http://www.billzilla.org/AE86page3.htm . me likes this thread, finally someone with knowledge is rattling the 4 valve fraternity

[The Real Roadrunner]

Doesn't say much on the page apart from a picture of all the Formula Atlantic bottom end parts + shimunder buckets and 2mm oversive valves.

no cam specs etc which is where the grunt is made (generally). nor can i see 185whp being acheived thru the factory cast exhaust manifold.

Did it ever go on the dyno Bill or is that just a guesstimate of what it should make? im not saying it can't make the power i just don't think it would as it was in the car.

[Billzilla]

No, I mean 185hp at the flywheel. O'Shannessy's engine has something like 40hp more than that I think. My engine has made 140hp on a chassis dyno, but they vary so much any figure you see is to be taken with a grain of salt.
The only way you'll get 200hp at the wheels of a 20v is if you bolt the wheel to the back of the crank.

[The Real Roadrunner]

The only way you'll get 200hp at the wheels of a 20v is if you bolt the wheel to the back of the crank.

I guess ill have to dig through the copious amounts of dyno sheets to find them. Its Fwd so that chews less hp but it was definately 200hp atw and it was running AO48's on the front at that time which aren't exactly dyno friendly either.

yeah 140hp atw is easy as, heck my stocker RWD has 114hp with just a 2" exhaust on it and no other mods, but once you start to go past 160hp it starts becoming hard to find what to fix next for more grunt.

cheers
linden

[oldcorollas]

for 160Nm from 4A. crank powah (hp and kw) (oh, and using petrol.. not methanol or race fuel)
multiply by more if you think you can make it. (ie, if you think you can get 110%VE, multiply by 1.1... but i assumed peak power has lower than peak torque, so maybe 160Nm is ok guess).. since we are thinking about peak powahs)

[Billzilla]

That's pretty close to what I got, Stuart.
FWIW just a couple of examples as to how useless quoting wheel power from a chassis dyno is - with that same 4AGE on one dyno it got 110hp (the guy told me that was about the same as an Altezza gets) and on another 140hp.
My racing car engine has made 133 wheel hp, and has subsequently been run on an accurate engine dyno. If both figures are correct, then my drivetrain is about the most efficient RWD on earth, with only about 8% losses .....
Yeah, right!

[KARNAGE]

you were saying anyone looking for big horsepower numbers uses the bigport heads and i know you are talking about na applications but the rigolli's built the fastest corolla in aus with a 20 valve and i know it is turboed but it hasnt got crazy lag from running a huge boost it does it with good engineering so my point is 20 valve heads with the right set up can be good as well

[Billzilla]

you were saying anyone looking for big horsepower numbers uses the bigport heads and i know you are talking about na applications but the rigolli's built the fastest corolla in aus with a 20 valve and i know it is turboed but it hasnt got crazy lag from running a huge boost it does it with good engineering so my point is 20 valve heads with the right set up can be good as well

Wrong point - a forced induction 20v will be a better head than a 16v big or small port.

[old_school_jap1]

why's that??? i was under the impression that the basics of a turbo are to get as much air in as you can and the best at that is the bigport?

[-GT-]

Curtain area: with the extra intake valve is much greater - less of an advantage NA as the flows are a lot closer and interfere with one another more than 16V; boost overcomes that somewhat.

Edit: You're right about basically getting as much air in as you can, however the differences in flow behaviour between negative (relative) manifold pressure and positive manifold pressure (NA and boosted) play to different features of the 16V vs 20V; some things cause minimal issue in one but hold back the other, and vice versa.

[oldcorollas]

formula atlantic was abotu 240hp at 10500rpm? while they may not be the ultimate, they are not bad. also agrees with "theoretical" curves above..

Linden, what rpm was the 20V pulling 200 at the wheels?
give say "10%loss" = 220hp = 9700rpm power peak?

how much bottom end do you lose with cams needed to support that? nothing under 5000? 6000?

[The Real Roadrunner]

9500rpm peak, VVT still functioning so it was decent above 5600rpm. id guess it was making 240hp at the flywheel (never had it engine dynoed) which would give you a 20% loss thru a fwd box. and from the laptimes it did the figures would be about spot-on.

it was aftermarket everything bar the head, block and crank so obviously not a cheap exercise and with all the supporting hardware would have cost about 25K+ to do.

anything under 5K it was a pig but it wasn't street driven so that wasn't a problem.

cheers
linden

[oldcorollas]

poor box must have been getting hot with a 30kw heater in there

pretty good effort to get 10% more VE than an FA motor tho! (or 8-9% "loss" and similar VE to FA motor)

of course it is possible to increase VE higher, but it doesn't happen often, especially at such low rpm
(i'm not knocking.. just musing )

kinda unrelated, but related for noobs
some background on the new atlantic motor
http://www.champcaratlantic.com/News...le.asp?ID=1956

Different components will be replaced at each 2,000-mile rebuild.

"Each rebuild will be different because we throw away components like pistons, valves and springs every time," Wood said. "The cams will be replaced every second rebuild, and the rods every third build. So we wanted to go through the first cycle of three rebuilds here on the dyno. None of the engines that race next year will get beyond the second rebuild, so if we go through the third rebuild on the dyno before the first race we're reasonably comfortable that will keep us with enough buffer zone to have a reliable first year.

this is for an 8500rpm rev limit (but long stroke)

how long do atlantic spec motors last? 500km of racing?