Jenvey Throttle Bodies On The Mi16 - The Results

[Batfink 201]

Agree its safer on track to compare. It is however difficult to compare two vehicles due to so many different variables. For starters Jons car is much lighter than standard, his suspension set up will be different and so will his tyres. Add all that to his serious turn of pace on track means it's difficult to compare even on track. He carries more momentum out of corners than most people do, meaning that he will look even faster on track. See my point?

 

Rich_w's suggestion of 1/4 miles times would give a more accurate comparison but even then you need to factor in good starts and gear changes.

 

not really as suspension setup and tyres plays a very big part in 1/4mile times too

Slicks can gain you a second for example

[Kev-G 1]

Agree its safer on track to compare. It is however difficult to compare two vehicles due to so many different variables. For starters Jons car is much lighter than standard, his suspension set up will be different and so will his tyres. Add all that to his serious turn of pace on track means it's difficult to compare even on track. He carries more momentum out of corners than most people do, meaning that he will look even faster on track. See my point?

 

Rich_w's suggestion of 1/4 miles times would give a more accurate comparison but even then you need to factor in good starts and gear changes.

 

It wasn't meant to be an exact science.....

 

If someone has an extra 30 BHP you'll see that on the track regardless of how much quicker they can corner....

 

Indeed it's likely that within the 25 or so cars that there will be some with suspension (+ Driver!! ) comparable to Jon, with others with comparable power (real or otherwise)....

[PumaRacing 1]

Agree its safer on track to compare. It is however difficult to compare two vehicles due to so many different variables. For starters Jons car is much lighter than standard, his suspension set up will be different and so will his tyres. Add all that to his serious turn of pace on track means it's difficult to compare even on track. He carries more momentum out of corners than most people do, meaning that he will look even faster on track. See my point?

 

Rich_w's suggestion of 1/4 miles times would give a more accurate comparison but even then you need to factor in good starts and gear changes.

 

A sophisticated computer simulation program will do just that. The 60 foot time tells the computer the grip off the line and the 1/8th and 1/4 mile time and speeds provide sufficient information to calculate true power to within a percent or two. Obviously weight and gearing need to be known accurately. When David Vizard tested the computer simulation program I wrote about 15 years ago it nailed the power of his daughter's drag race car to within 10bhp on a 500 bhp engine that had just been tested on a Superflow engine dyno. Actually it came up with the exact figure but that was more luck than judgement. A few bhp either way didn't affect the simulated performance on an engine that powerful. Since then I've refined the program with moment of inertia calculations for flywheel mass, it can handle headwinds and slopes and recently I added the ability to model cars with downforce so I could simulate F1 cars properly. That showed up something quite interesting but is a story for another time.

 

If you make a bad start or the track is slippery this all gets accounted for in the 60 foot time.

[Toddman 0]

Interesting results - thanks for sharing.

Obviously the ideal thing is for this car to be run up at emerald so we can do some REAL comparisons and lay aALL the questions to rest.

 

I am curious why some people think having bigger injectors will give mor epower over std injectors though as I know an mi running std injectors producing over 200BHP at emerald. And it has std plenum which backs up Pumas point about TB gains.

 

Cheers

Luke

[Anthony 1,000]

I am curious why some people think having bigger injectors will give mor epower over std injectors though as I know an mi running std injectors producing over 200BHP at emerald. And it has std plenum which backs up Pumas point about TB gains.

Must be running above standard fuel pressure then, as the standard 214cc injectors are at 85% duty (ie nearly maxed out) at around 180hp @ 3 bar fuel pressure (standard), which is atleast part of the reason that people don't see more than that on standard Mi management...

[Toddman 0]

Must be running above standard fuel pressure then, as the standard 214cc injectors are at 85% duty (ie nearly maxed out) at around 180hp @ 3 bar fuel pressure (standard), which is atleast part of the reason that people don't see more than that on standard Mi management...

 

Yes Anthony running 4bar.

Which I beleive is what Jon is running with the bigger injectors.

 

Cheers

Luke

Edited March 8, 2006 by Toddman

[Dom9 2]

recently I added the ability to model cars with downforce so I could simulate F1 cars properly. That showed up something quite interesting but is a story for another time.

 

Start a new thread, that sounds interesting... Does it take into account total downforce or is there a moment associated with the front and rear aero balance? I spoke to Willem Toet a couple of years ago and he told me that F1 cars do not have a linear relationship between downforce and speed, despite regs being brought in to stop wings being able to bend much, this also effects the front:rear split...

 

Anyway, that is off topic, but I think there are a few of us who would be interested in your findings if you discussed it in more detail in the 'general' section Dave!

 

 

I am curious why some people think having bigger injectors will give mor epower over std injectors though as I know an mi running std injectors producing over 200BHP at emerald. And it has std plenum which backs up Pumas point about TB gains.

 

This is what I was getting at in one of my other posts... Could it be spray pattern? Could it be that the larger injector is open for a shorter time so the fuel gets srayed into the chamber faster and so mixes better? Maybe it is atomised better? Would be interested in some bcak to back tests! Isn't this why sequential injection systems use very short opening times, to make sure all the fuel gets in the cylinder ASAP before the valve closes?

[phatgti 0]

I would imagine that a 214cc injector which is fueling 200bhp must be open basically all the time even with 4 bar fuel pressure (are the fuel lines rated this high? most standard stuff is rated to around 50psi, 4 bar is nearer 60psi).

Edited March 8, 2006 by phatgti

[C_W 3 1 Cars]

It wasn't meant to be an exact science.....

 

If someone has an extra 30 BHP you'll see that on the track regardless of how much quicker they can corner....

 

Not necessarily, although I'll admit Bruntingthrope usuallyt does favour the more powerful car that can stretch it's legs (although not sure of the layout this year, last year had a huge straight) but even down that it seemed as though most of us were similar down the straight (as most were Mi16s this year).

[Kev-G 1]

Not necessarily, although I'll admit Bruntingthrope usuallyt does favour the more powerful car that can stretch it's legs (although not sure of the layout this year, last year had a huge straight) but even down that it seemed as though most of us were similar down the straight (as most were Mi16s this year).

 

Std. Mi's or std. + modded?

 

If someone has an extra 30BHP then this WILL be noticable....Everything else being equal then the more powerful car will show....There will be other cars there with comparable engines (less TB's), tyres, suspension etc.

 

Indeed it shouldn't matter on the length of the straights - That only shows top-end power - Area under the curve will determine the faster car.

 

IIRC JERAM's car could be mapped to anywhere between 150 + 170 @ wheels by changing the cam timing (figures are not overly important to the scenario) - It was mapped to produce the maximum torque. This means that the headline figure is not dramatically different to a std. Mi. Now, we are both comparable (both in weight + driving!!), and Knockhill is one of the twistiest tracks in the UK - His car will disappear from mine....The conditions are the same for both cars + the more powerful shows.

 

Fact is Jon has before and after figures + he has a 16% increase in power....We'll see how it goes..

[Dom9 2]

I would imagine that a 214cc injector which is fueling 200bhp must be open basically all the time even with 4 bar fuel pressure (are the fuel lines rated this high? most standard stuff is rated to around 50psi, 4 bar is nearer 60psi).

 

But that 214cc is presumably quoted @ 3 bar... Assuming there are no losses, at 4bar you would get around 33% extra flow, so the same injector would be 285cc @ 4bar... As for the fuel lines, that's a good question, I bet most people never look into that, although a lot of people invest in braided stuff anyway!

[Toddman 0]

Pretty sure the car is running braided hose and fuel lines anyway as it is a race car and ran all last season without any problems.

 

Cheers

Luke

[Adam B 0]

Theres got to be a point though surely when the injector will become restrictive by design regardless of pressure?

 

If i remember hes using bigger injectors as otherwise the length of time the injector is open is too long versus the valve opening time.

[Toddman 0]

I think that is the point that Dom was making - however -

Jons engine has std duration cams?

The engine I referred to runs GRP A cams so I expect quite a bit longer duration - so the question is would even more power be released by switching to bigger injector running at a shorter duty cycle.

IF so could the fact that Jons engine is using bigger injectors with shorter duty cycle be a reason for the massive hike in power as this seems to be the only mod apart from the TBs?

Just a thought.

 

Cheers

Luke

Edited March 8, 2006 by Toddman

[kate205gti 4]

Injector sizing

 

As a rough guide to power output, take the injector flow in cc/min and divide by 5 then multiply by the number of injectors.

 

Example: 220cc/min divide by 5 = 44 x 4 injectors = 176bhp

 

off the emerald site how does fuel pressure affect that?

[Dream Weaver 2]

Injector CC is usually measured at 3 bar IIRC, so I would guess you divide by 3 and timex by 4 to get the cc/min at 4 bar???

[B1ack_Mi16 67]

Injector CC is usually measured at 3 bar IIRC, so I would guess you divide by 3 and timex by 4 to get the cc/min at 4 bar???

 

Nope....

 

That would have been the case if it was a compressible fluid, but fuel is more or less incompressible.

 

So a 214cc injector @ 3bar = 214 * (4/3)^0.5 = 247cc @ 4 bar.

 

So with 4 bar pressure it may fuel enough for approx 200bhp.

[PumaRacing 1]

But that 214cc is presumably quoted @ 3 bar... Assuming there are no losses, at 4bar you would get around 33% extra flow, so the same injector would be 285cc @ 4bar

 

Tut. I thought you did flow stuff for a living.

[petert 554]

Flow is proportional to the square root of the pressure. That's why an increase in pressure does very little to increase flow, only putting more strain on the pump. Have you ever heard a 205 pump at 4 bar? They're not happy chaps.

 

ie

 

square root of 40 psi = 6.3

square rrot of 30 psi = 5.5

 

6.3/5.5 = 1.145 or 14.5%

 

You'd think the difference bewteen 3 and 4 Bar would be greater, but not so:

 

square root of 58 psi (4Bar) = 7.61

square root of 43.5 psi (3 Bar) = 6.59

 

7.61/6.59 = 15.4%

 

(which incidently is exactly what Black_Mi16 said)

Edited March 8, 2006 by petert

[Toddman 0]

Hmm.

Well the car runs a Bosch motorsort fuel pump, std mi injectors and I am almost sure 4 bar no more and gives a good bit more than 200BHP at emerald.

Std exhaust manifold as well.

 

Cheers

Luke

[petert 554]

15% more fuel would no doubt get you to 200hp, but as you said with a different fuel pump. It's been my experience that the 205 pump gets very upset after 3.5 Bar. If you can tweak it up to 3.3 Bar with an adjustable reg. then fine, but after that it's bigger injectors.

 

Trying to extend the duty cycle is also useless, 85% is maximum. It's possible to change the injection pulse from 7.5 to 8.5ms on an Mi16 at 7000 rpm, but the AFR stays the same.

[Mattsav 1]

There's no point in comparing the BX that made good power on a std inlet at emerald.

 

IIRC the cams are 254deg@1mm with 11.5mm of lift (I've measured the profile) and it has Omega forged pistons. It has some headwork as well but from looking at it the only gains will be on the exhaust side.

[Jonmurgie 2]

Just to jump in... so if I'm running 4bar of fuel pressure the standard pump won't last/work at that? What's likely to happen then? I've still got a surge tank to fit in the fuel system and that includes fitting another fuel pump for taking the fuel from the surge tank to the fuel filter/rail... should I get on and do that then you think?

[Dom9 2]

Tut. I thought you did flow stuff for a living.

 

LOL! It didn't even make sense to me while I was writing it... Guess I shouldn't expect much in my bonus package next month!

[kate205gti 4]

Just to jump in... so if I'm running 4bar of fuel pressure the standard pump won't last/work at that? What's likely to happen then? I've still got a surge tank to fit in the fuel system and that includes fitting another fuel pump for taking the fuel from the surge tank to the fuel filter/rail... should I get on and do that then you think?

ive been running 4 bar on the original (standard) pump since the tbs went on in 2004 no problems so far but ive probably jinxed myself now

 

the FPR is an uprated one though as are the unions to the filter