High revving BT 20v???

[slideways]

The objective is to build a BT 20v that can rev to around 9000/9500 Rpm.8|

Bottom end will be standard crank with the usual strengthening and balancing treatment, good bearings, forged and balanced rod/piston combo.

What C/R is good for this

What cams would I be looking at to make power with these revs,

What valve train mods should be looked at with said cams?

Are there any uprated oil pumps available of the shelf?

Do you retain the vvti?

Do the T3 velocity stack hit the brake booster in an AE86?

Best Ecu option for a 20v?

Also has anyone got any build info on Sexy16's 10,000 rpm coupe?

And yes have searched a shirt load, and their is no definitive information.

[Sam-Q]

you can forget the standard rods no matter what you do to them. Get spool or something

The 20V is a simple engine most ecu's will be fine, Wolf usually has issues though.

You can shim the stock oil pump for more pressure.

Stock pistons are fine.

Cams around the 300 degree duration as a very rough guess? with adjustable cam gears and no VVT anymore.

[lo_rolla]

Shouldn't you decide what power you want and go from there?

[Sam-Q]

forgot to mention trd valve springs and upgraded retainers would be the go also.

[lo_rolla]

TODA Inner Shim Kit - Springs, seats, collets, retainers, buckets and shims isn't toooooo expensive. I'd imagine cheaper then TRD bits, at any rate.
Well, for 16V at any rate.

[Sam-Q]

20v has "inner shims" stock though?

[corknose]

i know wideslider (ben) has a standard bt20v and he revs it to 9000rpm with a haltec computer.

[lo_rolla]

Well, don't I look stupid. And besides the fact I was talking about 16V, so I didn't factor in the price of 4 extra buckets!
I don't know what they do with 20V, I've only ever researched for 16V.

[slideways]

Sorry sam I meant crank not rod. I know the bt rods are piss weak.
Also is the weight of stock vs forged pistons of any concern?
Is there a difference between the 16 v and 20 v 7 rib blocks?

[Sam-Q]

lo_rolla: I thought you where just giving an example not saying to directly get the 16V kit so it didnt seem stupid to me.

slideways: the stock crank should be fine with 9000RPM, but some race prep would be good. Just to be safe don't get an aluminium crank puley. I know there's lots of debate over if your hurts your crank long term or not but I say it's not worth the risk for trivial if gain from having one. I would of thought in the past that piston makers would go out of their way to make something light, but from what I have seen this isn't the case. Also I don't agree with the high dome shapes on them which I think compromises the combustion chamber shape further. I like the idea of running a thinner gasket and shaving the head, old fashioned yes but I think it's superior in my crazy unexperienced theories

Blocks are the same

[4000GT]

Im running 12.5 CR

288degree 10mm lift cams

Supertec valve springs

Reseated valves

Stock rods

Stock oil pump

ARP rods bolts and flywheel bolts

TRD 0.8mm gasket

VVTi Retained

Any kind of solution without an plenum will rob power\

Link G4 ECU

Rebuilt bottom end

You need to look closely at header design and intake design for that rpm range, very easy to go backwards.

I will be revving to 9,000rpm in my application provided the header and intake design pull off.

[--Redwork--]

With big rpm big hp asspirated motors the length of the inlet and exhaust systems plays a major role in how much power you make, and how it is delivered...
As too does cam timing.... I gained 93hp ATW cause my cam timing was off....

Also stand off injectors make really good power gains... I dropped 4 mph at the stip when running injectors in stock location...


But to answer your questions...
CR: as high as you dare to go on the fuel of your choice.... I would imagine that anyhting over 12:1 would reach the point of zero gains as you'd have to remover to much timing to alow that high a CR...
Crank: as already stated... Get it knife edged and balanced.. as well as everything else too ofcorse.
Rods: Any good after market forged rod.. eagles spool ect.
Pistons: that depends on what you wanna spend... factory ones would be fine.. I used stock ones in mine.. no dramas..
Cams: BIG.... 288+
ECU: Again depends on chice.... And what you can get tuned locally... Alot of ppl like Adaptronic.. I've run Microtech in all my cars. Wouldn't mind going to a Motec next time round though..

And why are your goals 9-9500 rpm.??
Really you should be saying... I want X amount of power.. RPM is only used to aceive your goals..... HP= torque x rpm..

[4000GT]

How do you figure 12:1 is that point? Based on using low quality fuel? You can easily run 12.5:1 or more with 98 octane pump or race gas or even low percentage Ethanol.

[--Redwork--]

Just personal preferance..
On a street engine I wouldn't run anymore than 12.5 on 98 pump..
Ethanol is differnet story... but seeing as the only place to get it up here is from a race fuels suplier its not really relavant..
Ethanol is the shit... If only you could get it in 85%+ from the local servo. :(

[4000GT]

We get it at the pump here... E10 though.

[lo_rolla]

I'll be having 12:1 CBY 5.5AGE. Will prob be higher as I've already machined my block like 4 years ago and the special grease I put on almost gone.
I plan on running E85, even though I have moral objection to ethanol based fuels....

[--Redwork--]

Why would any one have a moral objection to ethanol fuel.???

And We get e10 p here from the pump but its just shit... and if you take when next your at your servo you'll notice it say UP TOO 10% ethanol... Its not guarandted thats you'll be getting 10% and the fuel they mix it with is just rubish.

[slideways]

Shouldn't you decide what power you want and go from there?

Yep. But to get there I'll need the motor to rev to Around 10k

I intend on running ITB's and I might fork out for a custom tuned lenght exhaust manifold and have that port matched. Unless the TRD coppies are good in design???
Also is their any significant gains to be had from OS valves?
What is the HP/RPM limit of stock pistons?
ideally I would like to get this motor to rev to 10 k but am not sure at what point it becomes dangerous with the parts mentioned.

[chrisjjanfd3s]

Hey guys,

Im really interested in this kind of stuff as i own a 20v and it seems to me like there hasn't been enough R&D done on this motor.

What kind of power figures would the above mods make, also would it be possible for some one to post up some dyno graphs :)

I thing that 86DC needs an engine thread where they post up what engine they have, what mods it has and a dyno graph

[Vizz]

... I would of thought in the past that piston makers would go out of their way to make something light, but from what I have seen this isn't the case. Also I don't agree with the high dome shapes on them which I think compromises the combustion chamber shape further.

Until now I've been guessing that aftermarket pistons were the way to go. You have some good points there Sam. Its interesting to hear that standard pistons can be up to the task. Might be able to save a few $, after some research of course. Thanks guys! :)

[4000GT]

Sam have you actually used stock pistons to 10,000rpm in a 20v?

[ae71]

toda power power up kit.

easy :D

[Frak]

Just personal preferance..
On a street engine I wouldn't run anymore than 12.5 on 98 pump..
Ethanol is differnet story... but seeing as the only place to get it up here is from a race fuels suplier its not really relavant..
Ethanol is the shit... If only you could get it in 85%+ from the local servo. :(


Recently dynoed a BT on E85, 13.0:1 comp, not what we expected, but goes well in car.

[--Redwork--]

needs more compression. ^^

[charged]

^^^^ no it doesnt :), the starter struggles already, as Frak said, dyno wasnt very satisfying with the figures, it goes well in the car . I will load up the in car footage when I get it from the nephew who lent me his camera for the last practice session

[Frak]

^^^^ no it doesnt :), the starter struggles already, as Frak said, dyno wasnt very satisfying with the figures, it goes well in the car . I will load up the in car footage when I get it from the nephew who lent me his camera for the last practice session


Sounded bloody sweet from the hill :)

[--Redwork--]

Just cause the starter struggles to turn it over just means the starter isn't strong enough..... ethanol loves compression.. The more the better.. Look at the compression ratio ppl are running with methanol and just come down alittle from there..

What power did it make.????

[sundee]

FYI - T3 stacks dont hit the brake booster, it would be a crap design if they did.
my BT20v turbo rev limit is set for 9200rpm
stock cranks, GZE rods, wisco forged pistons, stock cams, VVT still running, lightened flywheel - running haltech
took 3 years of bouncing of the limiter before a rebuild, engine was stripped and no damage at all - that was with gze pistons

[Delazy]

Recently dynoed a BT on E85, 13.0:1 comp, not what we expected, but goes well in car.


^^^^ no it doesnt :), the starter struggles already, as Frak said, dyno wasnt very satisfying with the figures, it goes well in the car . I will load up the in car footage when I get it from the nephew who lent me his camera for the last practice session

interesting to say the least...

still at the point where im deciding whether to just run 98ron or bother setting the fuel system up for the E85...

seen some quite ridiculous increases in power and torque in a few SR20's locally...both full e85 and 98/E85 custom blend...

[slideways]

So......

Oversize valves ???

[4000GT]

So......

Oversize valves ???

Yes its possible, I think my engine builder said there was 1mm of possible room there.

[charged]

Just cause the starter struggles to turn it over just means the starter isn't strong enough..... ethanol loves compression.. The more the better.. Look at the compression ratio ppl are running with methanol and just come down alittle from there..

What power did it make.????

It only made 103kw, but had a slipping clutch (input seal was leaking) and a farked pinion on the diff we discovered, also the ecu was giving a i/p signal fault at high rpm. So we think that may of contributed to the low reading. I know in the car yesterday the engine feels alot stronger, in my group there was a ls1 commodore with a fair bit of work cam, maf, exhaust, ecu and I had more squirt in a straightline than that.

[Sam-Q]

--Redwork-- : I think knife edging is a gimick, afterall the F1 cranks I have seen don't have it.

lo_rolla: whats the bore and stroke on that engine? also whats your top ring width?

4000GT : no not 10,000 but I have seen multiple reports of 9000RPM and higher, I will have those revs myself relatively soon. I wouldn't use stock with 10,000 but that's not what he is asking about, and if I did go aftermarket I would try and avoid the high dome shapes. I can't remember who it was but someone on here reported a power loss going to aftermarket pistons however that could of been anything though.

ae71: whats in this "toda power up kit" ?

sundee86 : as much as I dislike some T3 products it wouldn't be a bad design if the trumpets hit as they have the booster on the other side over there afterall..

slideways: I have personally seen a heavily powered head with 1mm oversize valves on the intake. I have serious doubts though to the benefit though as the middle valve is already heavily shrouded, maybe downsizing the middle valve with a large insert and upsizing the two outer valves might work....hmmm. But hey who am I fooling I have no experience in all of this stuff.

With all of these questions I have to ask why even bother with a 20V at all, I can't see the point of spending more than a few thousand on it when you can just get a Beams engine.

[4000GT]

Ah ok, so why cant he use VVT anymore? Its all about how the cam timing is dialed in... example, on my own 288 degree cams with VVT retained and clearance is fine.

[4000GT]

http://www.youtube.com/watch?v=yruZsFeLJKI

Here is a link of my old Toda 272 cams in a blacktop 20v VVT retained...

[--Redwork--]

F1 is differnt though Sam... They're dry sump.. so not all that much oil to get in the way.... And I think the massive rpm they spin at would cause them to not come in contack with the oil either..

But i'm not a f1 engineer so who knows...

[Frak]

interesting to say the least...

seen some quite ridiculous increases in power and torque in a few SR20's locally...both full e85 and 98/E85 custom blend...

I agree, some engines respond really well to E85, while others don't see much at all, I guess it's early days and after lots of people have been tuning with it we will see the outcomes and which engines respond the best.

[Frak]

But i'm not a f1 engineer so who knows...

You obviously don't come from Salisbury, South Australia! I used to have a weekend job at a Sprint auto parts store and every second customer was what I called an "F1 engine builder".........but they didn't know what oil they needed!

[Sam-Q]

F1 is differnt though Sam... They're dry sump.. so not all that much oil to get in the way.... And I think the massive rpm they spin at would cause them to not come in contack with the oil either..

But i'm not a f1 engineer so who knows...

yeah fair point, I wish someone had before after results with only that modded, which would never happen of course.

[--Redwork--]

I'm sure that knife edging woud give some form of gain.. weather its worth the effrot or not though is questionable...
I think as long as everything is balanced spot on and you have a good windage system in place you should be right..

[Gunner]

the weight removed, while knife edging, would see an increase, the 70% finished crank i have here is a shitload lighter than a standard crank.

[charged]

I'm sure that knife edging woud give some form of gain.. weather its worth the effrot or not though is questionable...
I think as long as everything is balanced spot on and you have a good windage system in place you should be right..

I dont think knife edging will be any real benefit for street use, maybe if you are very serious with a track car, my engine runs a stock crank and sump and never had a problem and Ive run at Mallala, PI and Bathurst and never had a problem. The bearings that came out of my import motor were like brand new and the thing had a hard life before I got the motor, oil changes were far and few between.

The 3s need a bit of weight taken from the crank as they are very heavy from the factory.

[charged]

here is the vid of the new engine/gearbox package, tyres were 4 yr old a048 advan which were well past their best.
jp3mQj8hbG4

[slideways]

I have been doing some more research and found what may be a shortcut to high revs.
Apparently ....(and feel free to jump in and stop me at anytime) a 4age crank will fit into a 7afe block. This allows you to shorten the stroke. Now before everyone start asking "What brand of crack do you eat?" I will discuss this vs. increased displacment later.

So with this 4a crank in a 7a block you are able to run longer rods, increasing the RTS ( Rod To Stroke ratio) to around 1.76-1.82 depending on the height of the pin in the piston. The 4a has a stock RTS of around 1.59. This ratio increase should allow the motor to rev higher with slighly less effort than stock geometry. It will result in a decrease in torque, with the increased potential for power at even higher RPM.

With a 4a knife edged crank, 7a block, 20v head and pistons or forged pistons?, custom rods and a better oil pump. C/R of 11.5. I see the potential for 10k RPMs with moderate reliability.

[Sam-Q]

I thought about this a while ago and someone I know has tried to tell me to do it because with the more ideal rod to stroke ratio the 1.2mm rings have a better chance of sealing in the high revs due to the combustion gasses being able to keep up. I have some doubts but I guess it wouldn't hurt. The crank would still be the weakness here though, I don't know what they do exactly to make them resist metal fatiage over time.

[slideways]

Yeah there is only so
much you can do with the stock crank. I guess you just do it all and hope or get an after market crank?

[Sam-Q]

I'm sure that knife edging woud give some form of gain.. weather its worth the effrot or not though is questionable...
I think as long as everything is balanced spot on and you have a good windage system in place you should be right..

you now I have been thinking the counterweight is there for a reason, it's to offset the weight of the recripricating part of the rod and the piston, therefore cancelling some of the force out. I would think that modding the crank might make the crank under more stress.

[slideways]

you now I have been thinking the counterweight is there for a reason, it's to offset the weight of the recripricating part of the rod and the piston, therefore cancelling some of the force out. I would think that modding the crank might make the crank under more stress.

As far as I have found, is that it will weaken the crank. The obvious trade off is you get less rotating mass thus more ability for revolutions. Knife-edging almost seems like an out dated practice as it was primarily done by all the ol' school 70's racers with big block engines. They did it so that they could get more 'drainage' of oil off the crank.

However I think that maybe their might be something to matching the counter balanced weight to the piston/rod assembly. But then again this may be hard to measure as the up and down movement of the piston may have a different rotating mass at the crank than its overall weight.

Also Knife-edging seem to have an affect on the harmonics of the crank, not something I want to deal with. I think it may be a greater benefit to have the crank balanced from the pulley at the front to the flywheel. And then give it a good old polish.

[Sam-Q]

well if it's for oil then how about a good old crank scraper, apparently proven to work on a 4age

[tuned86]

I've been curious about crank fillets as I do notice on the TRD/Atlantic cranks, the fillets tend to be thicker. Figured the fillets help avoid crank flex and improve reliablity.