Jump to content
The mkiv Supra Owners Club

What BHP when running BPU.


Geo

Recommended Posts

Not 400 at the wheels, that would be very unlikely.

My BPU auto makes 300rwhp on a RR and 350.5rhhp on a hub dyno. A manual TT should make a little more but not a huge difference.

 

You can claim 400 flywheel from just 270rwhp if you like, just allow 33% losses. A lot of folk's flywheel bhp claims are unrealistic.

Link to comment
Share on other sites

Not 400 at the wheels, that would be very unlikely.

My BPU auto makes 300rwhp on a RR and 350.5rhhp on a hub dyno. A manual TT should make a little more but not a huge difference.

 

You can claim 400 flywheel from just 270rwhp if you like, just allow 33% losses. A lot of folk's flywheel bhp claims are unrealistic.

 

I claim 25% losses on an auto. Only cause it give me a pub figure of 500bhp lol. If im talking to people who know what they are talking about its 380RWHP.

 

There would be. The Thor dyno is well known to be rather 'ego flattering'.

 

I know.....thats where ill be off to when im in need of a good print out to put on the for sale section. lol

 

edit: done the maths....im claiming about 32%....bless my heart eh!

Link to comment
Share on other sites

You got 380rwhp on a rolling road, right? Not a hub dyno?

 

380rwhp = 500 flywheel if you allow 24% losses. That sounds fair enough to me mate.

It's the folks that allow 20%-25% losses for a hub dyno that are kidding themselves, IMO.

 

Is the actual loss figure on a hub dyno a big can 'o' worms? I would have thought about 15%?

Link to comment
Share on other sites

Sorry, but I'm not understanding the difference between a rolling road dyno result (at the wheels) and a hub dyno result (at the wheel hubs)...are they not measuring the same point of the power train ? Is there that much loss between the hubs and the tyre footprint ?

Yours, thick but curious.

Link to comment
Share on other sites

Is the actual loss figure on a hub dyno a big can 'o' worms? I would have thought about 15%?

 

Well, using my car's results and 24% drivetrain losses as an example:

300 rwhp (measured at Surrey Rolling Road)

= 395 flywheel bhp allowing 24% drivetrain loss (24.0506329113924% if you want to be picky)

 

We can calculate that the

350.5 rhhp (measured at Thor)

= 395 flywheel allowing 11% drivetrain loss. (11.2658227848101%)

Link to comment
Share on other sites

Sorry, but I'm not understanding the difference between a rolling road dyno result (at the wheels) and a hub dyno result (at the wheel hubs)...are they not measuring the same point of the power train ? Is there that much loss between the hubs and the tyre footprint ?

Yours, thick but curious.

 

Massive amounts matey. The tyre grip on the road isn't free, it's friction, and lots of it.

 

My dyno place used a transmission loss of about 7% for a manual. I was impressed.

 

-Ian

Link to comment
Share on other sites

Sorry, but I'm not understanding the difference between a rolling road dyno result (at the wheels) and a hub dyno result (at the wheel hubs)...are they not measuring the same point of the power train ? Is there that much loss between the hubs and the tyre footprint ?

Yours, thick but curious.

A hub dyno makes no allowance for the weight of, and the other losses caused by, the wheels and tyres. You wouldn't think it would make a huge difference , right? Neither would I, but it seems to if you compare people's results.

 

At the end of the day, any dyno (RR or Hub) can be adjusted by the operator to give inaccurate and flattering results. Giving inflated power figures is good for business - people like good news.

Link to comment
Share on other sites

Have a look at this thread:

http://www.mkivsupra.net/vbb/showthread.php?t=76414&highlight=midlands+rolling+road

Think these figures are about as accurate as you'll get on a RR dyno, there was 2 stock cars, 1 uk and 1 jap which both made just over 300bhp, a couple of bpu which made around 350 - 380 and mine which is really bpu+ made 418. The two cars with hybrids made 440-450bhp

Link to comment
Share on other sites

Im BPU, with a mapped emanage will that eek out an extra 2 or 3 BHP or something? im still trying to work out the need for a mapped ECU with stock turbo's

 

Mine was overfuelling by a crazy amount (as they do) so I'd imagine another good 10bhp or more is possible through fuelling alterations.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.