[supra4life]

the mk4 na is about 200 lbs less than the TT version. A stock TT can run about high 13s 1/4 mile and the stock NA best time is about mid 14s 1/4 mile. With the weigh different, I wonder if there is a way to shave of some lbs and plus a bpu, the NA possible can achieve the 13s range.

Any experts in here tell me if I am crazy or if this is possible.

 

[vreaux728645]

Car & Driver tested a ringer(turbo) that did 13.4 or so in the 1/4! I don't think 13's are too much for an n/a (13.5-13.8, but no one's produced a timeslip to date. The M3 is mighty fast & weighs quite a bit more than an n/a! There must be some one who with a knowledge of the M3's output curve tha will tune a modified (rebuilt?) n/a to do as well. I know that the n/a does not have the development of the M3, but with lighter weight & some tuning I'd like to believe a peak output could be produced @ the optimum engine speed to get that vaunted mid/low 13 time!

 

[Soupskees]

with major engine work...

i.e. head work, manifold, Jun cams, header,exhaust, gears, short shifter...etc. I have seen a few 13 timeslips.

Can the NA really hit a mid 14 stock? i thought it was like a 15 flat i dunno tho. Also whats the weight of the NA? 3150? or 3445?

 

[Xdreamer]

stock n/a supras are 3251lbs with a automatic transmission. and as for the major enigne work needed do you know if jun makes n/a cams? If so give me some info Thanks Brett

 

[Soupskees]

yeah Jun makes at least an NA cam gear...

i think they make Cams too, of course they are hella pricey and i know there might be a little mod needed on the exhaust(CAM) side.

Oh and are the manuals lighter? (3251)

 

[DaveH]

My car (auto/targa/leather) weighs 3445lb with 1/4 tank of gas. The rollbar weighs 80lb so without that extra weight is would be 3365lb. The only lightening I've done is remove the spare tire.

 

[vreaux728645]

So Soupskees, what type of head/manifold work is involved? The intake & exhaust isn't too bad cost wise, but pulling off the head & the associated machine shop costs could be a BIG deal. JUN cams can't be cheap either! Any chance you could get these runnin' n/a drivers to the forum?

 

[supra4life]

smaller tires

I wonder if a supra na stock really needs the big size tires(245x50x16). Other similar size and weigh cars do not require that big of a size tires. for example: Lexus IS 300 stock has 215x45x17 and way around. 300ZX stock has 225x50x16.

I am sure you can shave of some lbs being change to a smaller set of tires. This in itself will involve 1/4 miles run.

 

[Soupskees]

there is a port/polished manifold that may also be made by JUn i need 2 check on that

yeah jun cam gears are like 500 a set and i think if u get new forged pistons u can get a really really high compression out of our 3.0 liter.

 

[Xdreamer]

the manual n/a's are 3215 and the uto's are 3251

And as for cam for the n/a you have to get the right type of only really can get them, overseas or have them made.

the cams sold for the twin turbo have a lower duration then what you really need cause it has the turbo puishing air fuel in the mixture where we uses a suction affect the engine makes.

twin tubo your pushing air into the engine

n/a+ air is begin ucked into the engine

So the cams you need have to be m,ade for a n/a in mind no turbo.

but you will need to raise your compression to atleast 12:1

which im currently doing im think of 13:1 but thats going to be to high i think for thstreet plus you n/a will have tp be pulling 9k redline with new cams and what not to make serious power.

so i need valve/spring and titanums retainers are in order.

also when you raise the compression and port/plish the engine you will lose low end torque but gain high end power

i know then new lexus has 10:5:1

compared to are 10:1

its do able if you really want power id use 14:1 but it would only be race car cause you need higher octance and race fuels so you detonate. plus you willl have o do some porting on the exhuast manfiold or get a japane 6:2:1 race header but after thje time your done you could have had sinlge turb supra which wuold give you about the same power poralby more depednig on varaitions . dpends on budget plans for the car. Also the exhuast cam uses a distributr cam gear. So you will have to mod this

 

[vreaux728645]

From my references, raising the compression ratio increases torque by about 4% per whole # increment. As far as the powerband, street engines are usually tuned for low & midrange performance.

 

[Xdreamer]

you say torque increases? meaning if i went with 12:1 i would see a 8% increase in torque? And if you add alot more air and have say a 3" inch exhuast you will lose torque. Thanks For the post and let me know

I wasnt sure if raisng the compression made more torque now i know.

 

[vreaux728645]

Thats what "tuning" is all about. How much power can you make & where do you want it. Thats also what those butterflies are for- a particular power curve. Note: since the IS300 racer will be operated @ high engine speeds, there's no need for vvTi and it doesn't have it! If you want to pass on the road atarting from a midrange rpm, go with a non turbo for your n/a, if its all out power at high rpms the tt ones may be the trick. Watch out for super high output developing cams too. High peak could mean soggy bottom end & soso midrange in the extreme cases.

 

[Xdreamer]

that butterfly you are talking about is it open or closed at wot?

And wouldnt taking out make me loss alot of low end but maybe ill gain the top? I dont want to take it out until im sure. Thanks Brett