Discussion: Blacktop 20v: The road beyond 200hp

[adamaw11]

the aim here is 200+ hp. that wont happen on an n/a 20v on pump gas.

If you read the thread about that ke25, he actually says that 121rwkw was made with bp ultimate, do you not consider that 'pump fuel' ? this is even a north-south setup so the drivetrain loss would be more, but it works out to 200+ hp at the engine even using a fwd loss factor of 1.25. thats enough to convince me that its not entirely impossible to get 200 crank hp on pump fuel.... since it appears to have been already done.

[kingmick]

for which cam specs? surely it depends on dynamic compression more than static?

Depend were you are going to try an make the power you want! if you going to rev the neck off it lower it but at most lifts and durations exept for the extreem end 12-1 will be fine on pump fuel.

[oldcorollas]

Depend were you are going to try an make the power you want! if you going to rev the neck off it lower it but at most lifts and durations exept for the extreem end 12-1 will be fine on pump fuel.

12:1 with the stock cams will be unsuitable no? since the overlap will nto be enough to reduce dynamic compression enough to prevent detonation?

at high overlap, the dynamic compression is reduced, so you can use higher static CR.
at very high rpm, with high overlap, the high static compression should still be ok no?

i'm curious as to why you say seem to imply that higher static compression is ok for lower revs but not higher revs?

can you please explain more in terms of overlap and dynamic compression?

[Mr Revhead]

If you read the thread about that ke25, he actually says that 121rwkw was made with bp ultimate, do you not consider that 'pump fuel' ? this is even a north-south setup so the drivetrain loss would be more, but it works out to 200+ hp at the engine even using a fwd loss factor of 1.25. thats enough to convince me that its not entirely impossible to get 200 crank hp on pump fuel.... since it appears to have been already done.

121kw is 162 hp.
if talking wheel hp then thats a loss of 40hp.
which is rather a lot. like twice the loss of a C56

these engines make 140-150hp stock. getting another 50+ out of them on the same fuel wont be easy!

[Celica RA45]

i thought that 20 v that made 130 something was a 7age stroker out to 1900 cc ,well thats what i was told

[oldcorollas]

no pissing contest at all Kingmick. this is about information (or lack of it)
whether you are in the industry or not makes no difference, you either know or don't know.

saying that you can run 12:1 at low rpm, and you need to decrease it at high rpm, is a little vague (is it because you don't know?).

so anyway, to kick it off,
with the stock cams and compression, with 96 or 98octane, apparently there can be detonation problems (depending on air temps and such). if you increase to 12:1 with stockish cams, it will detonate. if you increase valve overlap, you will decrease dynamic compression, so at the same revs as before, it will be less prone to detonation, BUT, you either maintain, or lose, torque at lower rpm, because the tradeoff of overlap is lower dynamic compression at low rpm.

long overlap cams are better suited to high rpm (etc etc), but they have lower dynamic compression due to overlap, so higher static compression is needed to bump the dynamic compression back up to decent levels. at very high rpm, when you begin to get intake harmonics that have a positive pressure increase of maybe 6-10% will start to affect the dynamic compression you can run (and also the rate of charge heating during compression, but there are excellent analyses of this in the knock detection work already available), but most 20V will not be running above 10Krpm.

of course with bigger overlap cams, 12:1 might be fine, but you would not expect the engine to still develop decent torque at 2000-3000rpm, since the dynamic compression with large overlap at low rpm is lower.

however, if you keep smaller duration cams, to keep engine in the say, 3-7000rpm range (ie, stock rpm range), then it seems reasonable that 12:1 will be too high static compression, given that stock is 10.5-11:1 on 100 octane. if you increase lift and cylinder filling AND compression then at these normal rpm, the detonation will likely increase...


However, i am intrigued as to your comments as to how 12:1 will be ok, and was wonderin gif you could qualify the "extremes" of lift and duration you talk about. you mean high lift low duration/overlap as well?
how high rpm are you talking for needing to reduce the static (and thus dynamic) compression? 10K? 12K? 8K?

what cam would you say is safe with a 12:1 static CR and down to what rpm?

[Billzilla]

One of the problems the 20v's have is that the 23mm cam buckets simply aren't big enough diameter to allow a big cam, and that limits the power.
The others are the flow interference between the three inlet valves, the poor combustion chamber shape, and the small squish areas.
The rest of the engine is very good though.

[gianttomato]

Bill, is there room to bore out the lifter bores to fit a 24 - 26mm bucket? I suppose the next question would be where does one source a 24-26mm bucket - motorbike engine perhaps? I suppose then at least you could run a bit more lift for the same duration?

But then again does the extra intake valve make up for this limitation?

What are the valve diameters of the 20V Blacktop and 16V 4AGE? What is the combined VSA?

I don't know - just thinking out aloud.

[gixer]

Bill the 23mm cam buckets are small, that's why we radius the edges and allows us to run more lift

[Billzilla]

Bill, is there room to bore out the lifter bores to fit a 24 - 26mm bucket? I suppose the next question would be where does one source a 24-26mm bucket - motorbike engine perhaps? I suppose then at least you could run a bit more lift for the same duration?

But then again does the extra intake valve make up for this limitation?

What are the valve diameters of the 20V Blacktop and 16V 4AGE? What is the combined VSA?

I don't know - just thinking out aloud.

You could get another mm or so out of them, but I'm not sure where to get the bigger buckets from, I've never looked.
The heads flow better than a 16v in just about every test you can try, but a flowbench is just a part of the picture, and can be misleading.
The curtain area of the 20v inlet is bigger, but again the kind of airspeeds you see in a flowbench aren't really fast enough to show the real picture.

[86er]

facelift and prefacelift silvertop heads are the same, its the intake manifolds that are different.

Thanks for correction

as far as octane goes well the addition of management is important factor in dealing with lower ron fuels, that said if evryone agrees on the 12:1 being either too high or the limit maybe a slightly lower compression may be sufficient. I am curious about specs of that 133rwkw 20v But look teh ke25 which is in whp thats over 160rwhp which is over 200 at crank in that rwd application, that motor is basically stock just trumpets, headgasket and he said a light port, and lightend pullies, I suspect an important factor in his numbers is the electric water pump and the high octane fuel, what are ur thoughts on the davies craigg pump, I would imagine the elimination of the water pulley is a great way to free up horsepower.


More on the compression to cams to determine reliability, prehaps the stock pistons with a thinner gasket and shaved head would be enuf of a bump in compression. stock blacktop is 11:1 so im wondering how the trd 0.8 gasket affects this with 11.5:1 comp would the additional lift of the kelford 298cam at .385mm lift is 10.03300mm show good gains with such lift or would one need a 12:1 minimum comp to take advantage of such lift, I would not like to go over this duration I would actually prefer to keep a good powerband and not have a engine thats too peaky. I wonder if kelford could grind a 288 cam with same lift (most likely i will email them) prehaps a 280intake and 288 ex both with 10mm lift. there 298 on is rated at 4500-9000rpm which i think is pretty good with tuning and the right length velocity stack and header length i think one could open up power curve for a wide power band. Now the reason for the higher ex cam i specified above is to also affect powerband in a positive way ( open it up) i recently read in a online discussion about 4ag and staggered cams its better to have a larger ex one for broader power band and to allow better flow out of head a area where 4ag can loose power. Any thoughts on this

Now as far oversized valves here are the only ones i know about
http://www.hachiroku.net/forums/show...ing+valvetrain
both 1mm over. take a look and u will see specs so let me know thoughts.

Bill what is max lift i can run is 10mm ok? and if not will radiusing the edge of bucket do the trick.

thanks all for replys and thoughts looking forward to views on the above thanks also i may reply some strange times as im in a different time zone thanks all

[oldcorollas]

btw, i have all three version of 20V throttles atm.. what angles do people want pics? the pre and post facelift silvers don't looks hugely different (on initial inspection) except fro the square notch...

or perhaps Celica RA45's 48's would be better

[86er]

btw, i have all three version of 20V throttles atm.. what angles do people want pics? the pre and post facelift silvers don't looks hugely different (on initial inspection) except fro the square notch...

or perhaps Celica RA45's 48's would be better

personally all angles that hilight port sizes and differences would be great

[oldcorollas]

no worries, i'll dimension them up as well, like the brake calipers.

[Mr Revhead]

btw, i have all three version of 20V throttles atm.. what angles do people want pics? the pre and post facelift silvers don't looks hugely different (on initial inspection) except fro the square notch...

or perhaps Celica RA45's 48's would be better

yeah thats the only real difference that im aware of. the facelift ones are a far better match to the ports in the head. how about a pic that shows that.