Project Supracharger

[Shane]

David, hats off to you mate. I know exactly how much work has gone into this, masses. My by comparison feeble attempt at achieving this a few years ago absorbed hours and hours and hours of time, and I am sure Barney's build was the same. So for you to see this through in a much more complex form and also to actually have the living proof that it can be done is a real achievement.

 

You have the UK's first Supercharged Mkiv Supra on the road and that in itself is something to be proud of.

 

I am positive the numbers will rise in time and i really hope the build proves reliable.

Edited December 15, 2012 by Shane
numbers not number..doh (see edit history)

[David P]

I just renewed my membership to see that dyno chart, really

Great work!

I presume 320 is at the wheels, the dyno chart says wheel torque, so I guess this is wheel power?

and that dip before 3000rpm is due to the autobox not letting to go full throttle and downshifting?

David, what sort of psi are you seeing at 1500-2000rpm?

I wonder if having so much boost of idle is killing the bearings

once again, I bow to your craftsmanship! you have fans in Poland

 

320 bhp is at the hubs, which is wheel hp minus tyre loss.

The transmission was locked in 3rd (1-1) so the dip before 3k must have been Dans right foot.

I will have a look and report on boost @ 1.5 - 2k.

@ tick-over has no boost.

The green line is the plot from my previous visit.

 

Ginqueer!

 

Well done at getting so far David, you are a tenacious old whatsit

 

I used to be tenacious young whatsit.

 

Cheers

 

David, hats off to you mate. I know exactly how much work has gone into this, masses. My by comparison feeble attempt at achieving this a few years ago absorbed hours and hours and hours of time, and I am sure Barney's build was the same. So for you to see this through in a much more complex form and also to actually have the living proof that it can be done is a real achievement.

 

You have the UK's first Supercharged Mkiv Supra on the road and that in itself is something to be proud of.

 

I am positive the number will rise in time and i really hope the build proves reliable.

 

 

Thank you for the kind words, I'm "well chuffed".

 

 

 

Now there are numbers, none of them make sense.

 

According to my reckoning the charger should be pumping 747cfm, which on a good day should be enough for 500bhp.

 

Crank pulley 6.78" - charger pulley 4.0" @ 112 cu in per rev x 6,800 rpm with correction for valve-overlap loss = 747cfm?

 

I will measure the pulleys to double check, but if someone else could check my sums it would be informative.

Edited December 15, 2012 by David P (see edit history)

[Shane]

320 bhp is at the hubs, which is wheel hp minus tyre loss.

The transmission was locked in 3rd (1-1) so the dip before 3k must have been Dans right foot.

I will have a look and report on boost @ 1.5 - 2k.

@ tick-over has no boost.

The green line is the plot from my previous visit.

 

Ginqueer!

 

 

 

I used to be tenacious young whatsit.

 

Cheers

 

 

 

 

Thank you for the kind words, I'm "well chuffed".

 

 

 

Now there are numbers, none of them make sense.

 

According to my reckoning the charger should be pumping 747cfm, which on a good day should be enough for 500bhp.

 

Crank pulley 6.78" - charger pulley 4.0" @ 112 cu in per rev x 6,800 rpm with correction for valve-overlap loss = 747cfm?

 

I will measure the pulleys to double check, but if someone else could check my sums it would be informative.

 

What does your boost gauge say you are boosting at?

[David P]

Boost gauge shows just over 11 lbs which is more than 4 less than calculated.

Edited December 15, 2012 by David P (see edit history)

[Dnk]

I thought the only difference from a turbo to a supercharger was that the turbo needs

to spool up where as the supercharger doesn't.

 

For any given boost pressure from either you will get the same hp figure

just delivered differently or have i got it wrong.

 

So 11 psi or just under 0.8 bar is 320 hp which is what a stock tt puts

out as near as damn it at the same boost pressure.

My guess would be if you crank up your boost pressure to 1.2 bar

you'll be near 400 hp.

It would be interesting to see if this is the case then the

maths would appear to be easy on what you need to do to make

500 hp

 

I am just going by jo bloggs engineering here so just my take on it

with zero investigation

Edited December 15, 2012 by Dnk (see edit history)

[David P]

It's volume that's important, boost pressure is just a side-affect.

 

The calcs I work out to be 747cfm and 150cfm = 100bhp, or thereabouts.

 

If the throttle-body to charger induction pipe is causing circa 15% reduction to flow, that would cost a lot in generated heat to compensate for and take more power to drive it.

 

Or I've got my sums wrong.

Edited December 15, 2012 by David P (see edit history)

[Dnk]

Get it back on the dyno and go to 1.2 bar and see, if it makes around 400 then

you have your answer

 

Or get it next to a stock tt on the rd and it should leave it for dead if its got nearly 200

hp more

Edited December 15, 2012 by Dnk (see edit history)

[David P]

It'll be back on the dyno with a smaller pulley for 1 Bar of boost, as soon as I've completed development of other parts of the project.

 

1 Bar is the limit at which I would expect the engine, supercharger and transmission to function reliably.

 

In the meantime, I'm curious to find the missing 150cfm.

 

The dyno figures are related to the boost figure, but the volume is not related to the flow per rpm figures.

Edited December 15, 2012 by David P (see edit history)

[Shane]

I thought the only difference from a turbo to a supercharger was that the turbo needs

to spool up where as the supercharger doesn't.

 

For any given boost pressure from either you will get the same hp figure

just delivered differently or have i got it wrong.

 

So 11 psi or just under 0.8 bar is 320 hp which is what a stock tt puts

out as near as damn it at the same boost pressure.

My guess would be if you crank up your boost pressure to 1.2 bar

you'll be near 400 hp.

It would be interesting to see if this is the case then the

maths would appear to be easy on what you need to do to make

500 hp

 

I am just going by jo bloggs engineering here so just my take on it

with zero investigation

That's based on the CR of a TT though, David's is an NA running higher CR than TT so I am not sure that you can make a direct comparison at the same boost levels.

[mattdavies]

Does a supercherge 'use' some of the energy created by the combustion process to turn, hence why turbos came round as they gain their energy from the exhaust gases, which is now 'waste energy.

 

I may be talking crap but just my undestanding

[wojtrek]

320 bhp is at the hubs, which is wheel hp minus tyre loss.

The transmission was locked in 3rd (1-1) so the dip before 3k must have been Dans right foot.

I will have a look and report on boost @ 1.5 - 2k.

so your transmission holds a gear even if you floor it at say 1800rpms? and I mean WOT. I doubt that, simply because looking at the dyno chart, you'll see that the torque at 2000rpms is at 320, which is more than peak torque at around 4800. Since I have a dyno and I have had many cars with automatic gearboxes on it, with me at the wheel, I can tell you that this looks like a typical automatic gearbox chart, that dip, high torque at low rpms etc.

 

but please check that boost at low rpms, since this is one of the advantages the SC should have over turbos

 

 

Now there are numbers, none of them make sense.

According to my reckoning the charger should be pumping 747cfm, which on a good day should be enough for 500bhp.

Crank pulley 6.78" - charger pulley 4.0" @ 112 cu in per rev x 6,800 rpm with correction for valve-overlap loss = 747cfm?

I will measure the pulleys to double check, but if someone else could check my sums it would be informative.

 

a 3 liter naturally aspirated motor that revs to around 6900rpms needs around 350cfm at max rpm, WOT (at 90% Volumetric efficiency) - according to many CFM calculators online.

so, to get 1 bar positive pressure (15 psi) the charger should flow around 700cfms.

 

depending on charge temps, fuel, ignition etc, that should net, in our 2JZ, around 450hp at the crank. this is more a guess work, not real calculations. I think it;s pretty hard to convert CFMs into HPs.

But I think most of you will agree that once you go single 450HP at 1 bar is more less what you get. If you have a huge turbo, you will have closer to 500hp and with small twins, you're closer to 400.

So more less 450 from 1 bar.

 

now, your SC revs at 1.69 the revs of the engine. that's around 11500rpm. looking at a M112 performance map (http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128487.gif)

11500 rpm, 0.7bar (11lbs which you have) it flows ca. 1160 m3/hour, which converts to about 680CFM.

now if a 2JZ really needs around 350CFM while naturally aspirated, and at 1 bar positive pressure 700CFM, then at your 0.7 bar (11lbs) it needs ca. 595CFM. unless of course, your engine's VE is different.

 

so, the SC flows 680CFM at the specs you provided, the engine needs around 600 from these calculations.

a stock 2JZ-GTE has 320hp at the crank and 323ft/lb of tourqe at the crank. and it does that with 0.7bar of pressure, so your kind of pressure.

 

if around 750CFM really equals more less 500hp, then your 600CFM equals to 400HP.

 

Now, we have to consider 2 quite important things.

1. You have 320 at the hubs, which probably is around 340-350 at the crank, BUT!

2. A supercharger needs power to rev, it eats up your crank HPs! Parasitic loss at 11500rpms at 0.7 bar is about 50HP (http://www.mediafire.com/conv/fe2f8b017ec84d1a11dff490fbb856a9514d50f15d61d66df7126eba4bed85f46g.jpg)

so, your engine produces about 390-400HP at the crank, so pretty good for that boost. but only 320 get to the hubs due to the parasitic losses and some power lost in the gearbox.

 

since a turbocharged supra does not have the parasitic losses of a supercharger (only that of a gearbox) your car should be more less as fast as a 350HP (crank) automatic supra.

 

if you want to add say 100hp, you would need to change your pulley set from 1.69 ratio to a 2.1 one. so if you leave your crank pulley, you need to change your SC pulley to 3.24".

but then your revving your SC to 14500rpm and making around 500 crank HP. the parasitic loss goes up to probably 70-80HP, so you end up with around 400 at the hubs.

 

you have a 3.8" SC pulley. this will raise the ratio to 1.78 and SC rpms to 12200rpms. you will gain appx. 50-60CFM so I'm guessing 30ish HP?

 

sorry for that long post

[garethr]

Does a supercharger 'use' some of the energy created by the combustion process to turn, hence why turbos came round as they gain their energy from the exhaust gases, which is now 'waste energy. I may be talking crap but just my understanding

IIRC it takes about 120bhp just to drive the blower on a Mercedes SLR.

[David P]

wojtrek,

 

Thank you for being long posted, that's answered my sums conundrums.

 

The transmission is controlled by Suprastick which is set to lock the torque-converter @ 2k revs.

 

It was in Manualised Mode, maybe Dan changed up from third? torque-converter is set to slip for .2 second @ gear-changes.

 

However, it's a bit slow and transmission functions are the next jobs on the priority list.

 

I'll make a video clip of the rev counter and boost gauge.

 

When the time comes, I'll drop the engine rev limit to 6,650rpm and see how it goes with a 3.6" pulley @ 12,500rpm.

 

Thanks again for your input.

 

Nastrovia

Edited December 15, 2012 by David P (see edit history)

[David P]

please check that boost at low rpms, since this is one of the advantages the SC should have over turbos

 

I've been too busy enjoying myself to make the vid-clip, yet full boost of 11lbs by 2.4k rpm.

Edited December 16, 2012 by David P (see edit history)

[wojtrek]

that's great what about below 2000? is it like say 8psi at 1800rpms, 5 psi 1500rpms?

[David P]

I've been too busy driving to notice, I'll make the video.

[David P]

that's great what about below 2000? is it like say 8psi at 1800rpms, 5 psi 1500rpms?

 

With the 4" pulley, no boost below 2k.

 

2k = 1lb

2.5k = 7psi

3k = 11psi

 

2nd gear pull from 1.5k, boost gauge second one down in pod.

 

Edited December 17, 2012 by David P (see edit history)

[kill1308]

I don't think you have enough gauges

 

PS - says the video is private

[David P]

I don't think you have enough gauges

 

PS - says the video is private

 

Ooops, sorted.

[supra joe]

Says content is blocked david.

[David P]

It looks good to me, but have opened it again.

[Chris Wilson]

Have you considered having a clutch like Mercedes do, to turn "off" the SC and reduce pumping losses when boost is not required, bypassing it? Would also be good if you get some meaningful boost from under 1800 RPM. Amazing thread of one bloke's perseverance!

[David P]

Have you considered having a clutch like Mercedes do, to turn "off" the SC and reduce pumping losses when boost is not required, bypassing it? Would also be good if you get some meaningful boost from under 1800 RPM. Amazing thread of one bloke's perseverance!

 

With the existing bypass-valve system the charger uses .5 bhp when not boosting, after I've settled on a pulley-size and chased the Gremlins out of the other systems, I'll see if I have enough steam to do a lap of upgrades and weight reduction of components.

 

When I swap to a 3.6" supercharger pulley, the boost should be up to maybe 14psi and begin sooner, in fact I think the current 'behaviour' of the transmission is keeping it off boost @ low revs.

 

The engine-conversion is now running fine and under observation, I want to just let it get on with it's job for a while and move on to the transmission.

 

First to second changes are too slow and I suspect the solenoids are gumming up, also, @ high revs maybe there are too many volts for the Suprastick to read.

 

Further to a two month wait, now two Parcel Force delivery attempts failed to find my address, the modified valve-body is presently lost somewhere at the Leicester Depot.

 

When the cows are laying down in the field and this eventually gets fitted and the over-volts 'maybe' issue resolved, I can then have a good fiddle with the torque converter settings and find it's sweet-spot.

 

I have over-legged the gearing too, I'll keep the 40 profile 18's yet swap the T.T. auto 3.769 diff, back to an N/A 4.083 Torsen with a T.T. flange.

Edited December 17, 2012 by David P (see edit history)

[wojtrek]

you DO have boost under 1800rpms, it's just that your gearbox will not let you have 100% open throttle and 1800rpms, when it sees that kind of throttle position the torque converter bumps the revs to around 2500, just like most automatic gearboxes from that time. Only these new autoboxes and DSG boxes will transfer all power from low rpms without the 'slip'.

That's the reason you have that dip on the dyno graph before 3000rpm, that's the autobox ecu not transferring all the power.

 

and 7 psi by 2500 is not really a valid readout, because the needle went past that mark just as the rpms were crossing 2500mark to the ECU's desired rpms.

From the SC characteristic it is simply not possible to have 11psi at 3000rpm and only 7psi at 2500.

 

I had a supercharged civic, 1.6 engine with 12psi boost, it made 265hp at the crank. It had a M62 eaton, so half the size of you SC, but it was half the engine.

so, because it was a manual, I could watch the boost rise with the rpms, and at idle rpms (from around 1000rpms) it already was at 3psi. 1500rpms 5-6 and 7-8 at 2000rpms and 10+ from 2500rpms, and I'm pretty sure this is what you'd see with a manual.

 

thanks for the video

 

edit: and it's true you don't really need a clutch on the SC pulley because you're using a bypass valve. Mercedes puts the clutch on cars without the bypass probably. The SC only eats significant power when compressing air, when it's in bypass mode, it just spins. Probably it's more than .5 HP but an insignificant number nonetheless.

Edited December 17, 2012 by wojtrek (see edit history)

[David P]

Nothing less than a video would suffice.

 

Christened my stick-on camera mount too.

 

I have programmable control of the torque-converter and plan to reduce stall-speed and lock-up to lower rpm's.