Neil's project NA-300 build

[Wez]

Some great info in here, sounds interesting, subscribed

[Neil-NA]

I have to admit I partially agree with David2009. Its perfectly possible to get the power you want without ITBs - they are not an integral part of the solution. I believe you have read my long monlogue on ITBs in the another thread. You can make an engine with a huge plenum and big lumpy cams with a single throttle body (provided it is not too restrictive) but its the ITBs that will give it the throttle response and idle stability that is a must-have for a road car.

 

If you are 100% focussed on top end power then losing torque at the mid-bottom end doesn't sound like it will be a concern. You will probably have to keep stirring the box to avoid falling into a big torque dip though.

 

I have done some rough hand calcs and I think you still have a choice to make over whether you tackle this by increasing the rev limit or upping capacity.

 

If you stroke to 3.4litres with a not-very-ambitious 11.5 bar BMEP, then 300hp rolls in at just under 6900RPM - possibly within the range of the stock valvetrain (albeit with a drop-in camshaft). Plus you will get a billet crank which will hopefully be stronger then the stocker, and you get a fatter torque curve in with the bargain and will have to do less optimisation of the intake and echaust systems.

 

However if you opt to keep the stock capacity, you will need to increase the rev limit to at least 7800RPM and ensure the engine can still breathe. This will mean new lighter pistons and rods and a new valvetrain, plus some intake and exhaust work to shift the tuning point to your new max power speed. I doubt that an off the shelf part will have the precise tune you need.

 

If you want to keep within the stock engine speed you will need to increase BMEP to nearly 14bar to hit peak power at 6500RPM and that is, unfotunately beyond the realms of what is feasible for the home tuner.

 

If I get a second I'll work out the NA Supra's BMEP curve to see what it manages in stock trim.

 

I really dont mind a drop in torque, aslong as she revs high and sounds good, if the ITBs turn out to not be needed then i can always use the other options available, as said i'm not after 300 at any cost, it would just be nice to hit it for under £10k, no more.

 

Thanks for all the input mate, i really appreciate the help as i am still trying to understand alot of what is needed.

 

I have read alot of threads on here and SF, i also have a look what the Honda boys have done as they seem to be the leaders in ITB cars.

 

Thanks again

 

will fuel wash be an issue with those throttle bodies......or will that nice speed six engine in the tvr for sale thread slot right in im just thinking outside of the norm here think how nice it would sound coming from the back of a supra

 

The option of the 3.6 TVR speed six engine had crossed my mind as a complete engine is £1500, but i want to stick with the GE.

 

Or you could look for a 2GRSE engine from the Lexus. 315bhp in N/A form, with cats and a Lexus OEM tune. Gorgeous VVTi engine.

 

I really want to stick with whats in the car if i can, seems a bit of a cheat to throw in something else.

 

Thanks for the help guys, glad to know i'm not getting truly slated for this

 

As stated i am in no rush to do things, if i get there then great, if not, well its only money and i can't take it with me when i die

[Nic]

How about starting with a 2JZ-GE VVTi, I don't think anyone has fitted one in a Supra in the UK. Stock they are 240hp and 344Nm at 5600rpm.

 

http://img641.imageshack.us/img641/8110/picture1ng.png http://img835.imageshack.us/img835/6977/picture2gcp.png

Edited October 19, 2010 by Nic (see edit history)

[Digsy]

How about starting with a 2JZ-GE VVTi, I don't think anyone has fitted one in a Supra in the UK. Stock they are 240hp and 344Nm at 5600rpm.

 

Can you get your hands on the full torque curve for one of these?

[j_jza80]

Or you could look for a 2GRSE engine from the Lexus. 315bhp in N/A form, with cats and a Lexus OEM tune. Gorgeous VVTi engine.

 

They do a 355hp Supercharged version too in the Mark X

 

 

There's always the 2JZ FSE too...

[Neil-NA]

Nic i thought the 2JZGE VVTI was 225bhp (i know you have posted pics but cant see them till tomorrow as i'm on tha laptop) did the yanks get the VVTI.

 

I really dont want to have to do an engine swap if i can help it, i would like to know i started with what was designed for the car and i have now modified it my way to my tastes, its not the right way to do things, but its how i do it lol.

[Chris Wilson]

I believe Chris Wilson's Zeus pushed 300bhp out of a 2l 4pot NA and he says the cams aren't *that* wild

 

Regarding ITBs, maybe you should have a word with Paul Mac, he's been beavering away at ITBs on his car, probably save you a lot of time and money if he can give you some pointers.

 

Are the high comp pistons nice and light? They'll need to be to support higher revs without fretting the conrod caps.

 

Good call on the ignition system, you'll probably have to try and retrofit the coil on plug setup of the non VVTi TT, and junk the dizzy.

 

Cam choice will be interesting to support higher revs - at least 264/264 to make use of up to 7000rpm, but depending on how you'll drive it, you might want 272 or even 280's. At least with no need for a dizzy you might be able to fit TT based cams.

 

The Vauxhall 2.0 litre car gives about 220 BHP tops, but it's far from wild. Still on hydraulic tappets and carbs. A 300 BHP 2 litre is a serious engine with serious build and maintenance costs and totally unsuited to a road car.

 

I would say forget huge revs, limit a 2JZ N/A on stock crank and rods to 7600. Without the cushioning effect of boost internal stresses are higher in an N/A in some ways. Throttle bodies will give better response, but you could probably get the same BHP figure on a single body, if the "figure" was the be all and end all. It'll need custom pistons, at least 10.75 to perhaps 11 to 1 compression, a lot more valve lift than stock and about 280 to 285 degrees duration. A good head porting will help, but to be honest the stock ports are pretty good. It should make three hundred on pump fuel, no problem. It'll never pass a legit emissions test, IMHO. It'll be peaky and a bit `orrible even in a six speed manual Supra shell, because of the sheer weight. It'll be pretty unusable in front of a stock auto box. It'll cost a lot more than you think. It'll be worth a lot less than you think.

Edited October 19, 2010 by Chris Wilson (see edit history)

[Digsy]

Comparing the torque curves for the GE VVTi and the standard GE might give some insights into what the GE is capable of. It depends whether the VVTi is there to provide more bottom end, or more top end, or a mix of both.

[Chris Wilson]

Just done a few rough calculations and I would think 330 BHP should be easily obtainable within a sensible rev limit. Making it "nice" to drive, fuel efficient and even remotely emissions friendly will be the challenges. Good mapping and experimentation with cam duration (costly as every cam will probably be custom ground) and cam timing should give something fairly decent though. Looking at the specs for an early 90's BMW M5 engine should give you some idea of where you should be heading.

[Digsy]

What engine speed did you assume for peak power Chris?

[Chris Wilson]

About 7000 to 7200 max, could be done on less I reckon, with some development work. I'd do one on lots of squashie and map carefully.

[Nic]

Can you get your hands on the full torque curve for one of these?

 

I'm doubting now whether those numbers are accurate they seem to vary a lot on the net depending where you look.

[Digsy]

About 7000 to 7200 max, could be done on less I reckon, with some development work. I'd do one on lots of squashie and map carefully.

 

That's about where the engine I mentioned in this post was at. Still no idea what went into it to make the power figure though.

 

I do know it had intake and exhaust VVT to make it more drivable low down, but it still had less bottom end torque than some smaller capacity engines.

[David P]

"How long till yours is ready for the dyno matey?"

 

Soon I hope!

 

Just waiting for the HHO system to arrive, then that and the water/meth injection will be fitted at the same time.

[rob wild]

Really interesting project Neil! I saw the other day my cousins 2.0l Built Honda n/a engine make 270 fwhp! And it's just incrediable in a 800kg Civic EG! You never know he might be at the next nw meet

 

So surely the 2jz-ge engine can be tuned well!

Edited October 19, 2010 by rob wild (see edit history)

[Guest SupraTroopa]

Best of luck mate - watching with interest

[Digsy]

OK, I've dug out the data on that engine I mentioned a few posts back. Firstly, I discovered that it is a 2.2 not a 2.0 litre, so the peak BMEP isn't as high as I thought. In fact it isn't any higher than the stock engine, but it has been moved to a much higher engine speed to achieve the peak power figure.

 

Without saying specifically which engine this was, I have put the general changes into the attached spreadsheet. This should give you a good idea of what you might be looking at.

High output engine mods.xls