[crazydriving]

what is the max boost preassure on a stock Eurospec supra...
and how many rwhp does a bpu supra with 20psi max boost preassue got?

 

[Gavin Loughton]

what is the max boost preassure on a stock Eurospec supra...
and how many rwhp does a bpu supra with 20psi max boost preassue got?

Euro/UKand US spec cars are broadly the same, engine, transmissions and turbo's are identical.

In the UK 18 psi is considered to safe limit for the turbo's and we have few failures. In the US however there appears to be many schools of thought and a lot of blown turbo's.

How much rwhp with 20 psi, the question should really be how much rwhp and how long for!

 

[Syed Shah]

Well said Gavin.

I agree, alot of US cars are running over 20psi, but power gains here are minimal and the turbos aren't built for it, unless you plan to go single soon, then stick at 18psi max.

At 18psi, you should have about 350rwph as long as you have a non-stock exhaust, no cats and a FCD, and of course a boost controller or bleeder valve to get boost this high.

 

[crazydriving]

but the euro supra got 330hp original? Does a bpu only gain 20hp??

 

[Silver Supra]

but the euro supra got 330hp original? Does a bpu only gain 20hp??

are you mixing RWHP and crank?
BPU will get close to 400RWHP ~ 470 crank.

 

[Syed Shah]

No, American dynos do RWHP as crank, so really that 400rwph is 400 @ crank and 470 is rubbish.

 

[mistersolo]

In order to get true crank horsepower you would have to have the engine out of the car and on an engine dyno. Us yankees don't like to take the engine out of the car to measure the horsepower. RWHP is the net power output to the road. All losses from transmission, differential, etc. are included in the RWHP figure. Therefore, when the approximate losses are deducted, you get approximate crankshaft horsepower. So 470 crankshaft hp, which is 150 horsepower more than the factory horspower, is attained by freeing up the exhaust and raising the boost 7 psi over stock.

John B.

 

[SCV8]

Every chassis dyno I've seen is driven by the wheels,thus giving wheel horsepower,not to be confused with sae crankshaft rating(which hasn't been used since the early seventies really,unless you're an engine builder).Current practice for manufacturers ratings comes by measuring at the crank with all accessories on,for awhile it was right after the trans,I believe,might be wrong there.
It's like measuring the weight of meat before you cook it.
These cars suck up about 35-40 hp through the manual trans,and about 70-80 through the auto,so add that to a reading from a chassis dyno to get something close to what the car companies use.
Euro ratings are DIN ratings,which are calculated a bit different,giving a more optimistic rating.

 

[Silver Supra]

No, American dynos do RWHP as crank, so really that 400rwph is 400 @ crank and 470 is rubbish.

Oh - I'm glad someone from England straightened us Yanks out as to how US dynos work.

D'oh. do your homework.
Dyno measures HP at the wheels (RWHP for the Supra).
Typical drivetrain losses are about 15% for 6-spd and 20% for auto.
If a BPU 6-spd dynos 400 RWHP, then crank is about 400/(1-.15) ~ 470 crank.
If a BPU auto dynos 400 RWHP, then crank is about 400/(1-.2) ~ 500 crank.

 

[Gavin Loughton]

Oh - I'm glad someone from England straightened us Yanks out as to how US dynos work.

D'oh. do your homework.
Dyno measures HP at the wheels (RWHP for the Supra).
Typical drivetrain losses are about 15% for 6-spd and 20% for auto.
If a BPU 6-spd dynos 400 RWHP, then crank is about 400/(1-.15) ~ 470 crank.
If a BPU auto dynos 400 RWHP, then crank is about 400/(1-.2) ~ 500 crank.

But one of the problems with this if getting confirmation of the RWHP of a stock MKIV dyno'd in the US. I have seen two figures quoted recently one of which was 305 RWHP(some 45 hp more than the other). Now correct me if I am wrong here but I can't see how you derive 305 RWHP from a 326 crank HP car, manufacturers figures remember.

To explain the British supra owners problem with US power figures derives from our dyno readings which indicate a RWHP from a stock six speed car of around 260 and a BPU figure of around 90 hp more.

US dyno's appear too measure hp somehow differently. From my observations I have noted that US HP figures, crank or rwhp, are roughtly 15% above that in the UK.

 

[Syed Shah]

Exactly Gavin, US dynos measure much higher, and you also have this "corrected" RWHP figure.

Basiclly, a stock 6sp should give about 260-70rwph and a BPU should give around 320RWHP max.

 

[Silver Supra]

Now correct me if I am wrong here but I can't see how you derive 305 RWHP from a 326 crank HP car, manufacturers figures remember.

I know that some other cars and particular model of cars are under-rated by the manufacturer.
FWIW, also see this listing of engine specs.

http://www.geocities.com/MotorCity/Pit/9975/dataBySubject/GasolineEngines.html#JZ-series

I notice that the Japanese model 2JZ-GTE is "voluntarily" under-rated at 280 hp. Also look at the "Aristo" JP rating and comments (rated 280, real ~ 350).
I don't know about the Euro-spec version.


US dyno's appear too measure hp somehow differently.

I can agree here to the extent that our two main brands of dynos (Mustang and Dynojet) yield different results.
Again, I would not presume to tell you what UK dynos measure.
I do know that I got 327 RWHP at low boost and no DP. I look forward to dynoing again now that I am BPU. I fully expect to show 380-400 RWHP at higher boost (18 psi).

BTW - As far as I am aware, our "corrections" to RWHP measurements (and even 1/4 mile times) are to bring them to a standard temperature and atmospheric pressure for comparative purpose - NOT to estimate crank HP.

 

[Syed Shah]

Yes, but the corrected readings are almays higher than the normal ones.

Anyway, the Jap supra was underrated, but there was no need to to this in the UK and US, so 320bhp is real, not underrated.

So how can a 320bhp car have 305rwhp?

 

[Silver Supra]

Exactly Gavin, US dynos measure much higher, and you also have this "corrected" RWHP figure.

Basiclly, a stock 6sp should give about 260-70rwph and a BPU should give around 320RWHP max.

I suggest a little homework in the Performance/Dyno section here.

Maybe those numbers work for your car, not for mine.

 

[Gavin Loughton]

US dyno's appear too measure hp somehow differently.

I can agree here to the extent that our two main brands of dynos (Mustang and Dynojet) yield different results.
Again, I would not presume to tell you what UK dynos measure.


Now this get even more confusing. Needless to say we are wishing to measure RWHP and too those ends it should be a fairly simple matter. However it appears that two brands of US dyno do not give the same results, (can I assume this is general knowledge?) and UK dyno's are diffirent again.

I wonder if a car that car designed, made and manufactured in the US dyno's fairly accurately and imported cars do not?

I guess that if you go a little further with this that dyno figures mean very little and the quickest and cheapest to get a hp upgrade is change your dyno.

 

[randy]

Now just a minute the Jap spec supra has 280hp or 320hp? and what does it mean voluntary? This hp is crank isnt it? Also looks like the jap spec has more torque at 3600RPM?

 

[ThomasKenyon]

Basiclly, a stock 6sp should give about 260-70rwph and a BPU should give around 320RWHP max.

I am seriously at a loss for words in regards to this guy's statments.

I bet there is not a single, well tuned, BPU Supra putting down only 320 RWHP.

Anywhere in the world for that matter!!

This thread is proof that driving on the wrong side of the road can have a dramatic effect on one's intelligence.

Too funny....

Thomas Kenyon

 

[randy]

Senior~ what about the jap spec? Also I definately second that!! We are definately making more than 320RWHP with BPU!!!

 

[Syed Shah]

Think what you like, US dynos measure way too high.

As to the j-spec, it has more torque than the euro/US Supras, but less BHP, it also has smaller injectors, fuel pump etc.

It is (stock) about 300bhp, not 280bhp. Of course, on a US dyno, this would probably be alot more.

 

[Gavin Loughton]

I am seriously at a loss for words in regards to this guy's statments.

I bet there is not a single, well tuned, BPU Supra putting down only 320 RWHP.

Anywhere in the world for that matter!!

This thread is proof that driving on the wrong side of the road can have a dramatic effect on one's intelligence.

Too funny....

Thomas Kenyon

Come too the UK there are loads of them! Please read the messages above and make sure you understand them before you post ill considered remarks.

Isn't this just typical of this site, there are a few people trying too discuss an issue and in piles one (or more) member(s) who can do no better than to contribute a handful of mindless insults and and a bunch of rolleyes.

Just to make things worse the major offender on this thread is one of the moderators....you should be ashamed of yourself!