For the 'natural aspirators' - How tuned is your engine?

[Kozy]

nsa said:

Has anybody suggested starting a Wiki for this?

Was thinking about this this morning, seems to be enough interest actually!

Here's what I am thinking about for showing the some trends in the cost of tuning.

Original PI across the X axis, Upgraded PI up the Y axis, size of the bubble is the cost.

I just guess at some of these figures based on what I am familiar with, but I think we can see how it would end up.

Edited by Kozy on Monday 14th October 11:33

[Kozy]

cirian75 said:

just popped in the old Honda 2 stroke NSR500 in

1769

Well that's cheating isn't it, it's got twice as many power strokes!

[Kozy]

BaronVonVaderham said:

Roadcar: 754 (RS Clio 200 - 82.7, 4, 200)

Racecar: 326 ('91 Mini Cooper - 70.6, 4, 63)


Time to swap lumps!

Fascinating thread OP.

What is the highest value so far for a stock N/A car?

AFAIK the Ferrari 458 at 820.

Thought it depends on whether you count the Caterham R500 at 927 as 'stock'...

[Kozy]

Mr2Mike said:

Peugeot 205 Tarmac rally car, 275bhp from 2.0L engine with 88mm bore gives a PI of 916.

Unfortunately it would have a fairly low score on the reliability index.

Nice! What was it as stock, Mi-16 motor I'm guessing? Any idea how much that cost to build from stock?

[Kozy]

nsa said:

Definitely. Start one . I'll do it if you don't want to. I usually enjoy reading about stuff like this in the Technical area. I notice 300bhp is here already, the other guys from there will probably be along soon. Get your hard hat ready!

If we were to do that, it'd be worthwhile putting all the details in, bore, stroke, cylinders, torque, power, PI etc. One for standard engines and another one for modified engines, which would include the before and after figures and costs involved.

I'll have a look at it later.

[Kozy]

nsa said:

Definitely. Start one . I'll do it if you don't want to. I usually enjoy reading about stuff like this in the Technical area. I notice 300bhp is here already, the other guys from there will probably be along soon. Get your hard hat ready!

OK, started one for factory engines, if everyone would like to add theirs!

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

I'll start a modified one later.

[Kozy]

otolith said:

Has anyone done this?

http://bac-mono.com/specs.php

943.

[Kozy]

otolith said:

Yes - beats the R500 - but are these very highly tuned, low volume engines really "production"?

Valid question. I would say yes, insofar as you'd trust the figures (no pub dyno outputs) and (AFAIK), you'd get a warranty with them?

[Kozy]

So you don't believe that BAC or Caterham are actually making the figures they are claiming?

They are impressive figures, certainly enough to question, but you'd hope they were a bit more credible than Billy Two sts down the pub who's 2 litre Astra puts out 340bhp...

[Kozy]

XJ Flyer said:

stevesingo said:

6.5 litre and only 485hp-500lb/ft.

Not very efficient is it!

It depends on the definition of 'efficiency'.IE an expensive screamer or relatively low revving,so long lasting,affordable,torque monster.

Well I make that a 102.5mm bore which gives it PI of 595, which is pretty respectable to be honest.

[Kozy]

AW111 said:

Kozy : could you add a column to the wiki for theoretical max power, ie bhp x1000 / PI?

That would be the max power you could extract from that engine according to your formula.

Eg the Toyota 4age stands at 649 PI with 165 bhp, so theroretical max is 254 bhp.
These engines (16 valve version) were used in Formula Atlantic, and gave about 240 bhp in rev-limited form, which fits well with the "ultimate" power of 254.

In fact, any 81mm bore engine comes out at 254 hp max!

Yep, that's what most stock bore Honda B series engines max out at too!

I think it's probably a bit too much info for the Wiki, but if people are interested a link to the article is there and they can look it up.

[Kozy]

I've been working on a version of this for boosted engines.

I'm not sure on it yet, because of the difference between peak boost pressures and boost pressures at peak power, but here it is regardless as a test page:

http://blackartdynamics.com/EngineLimitsFI/Index.p...

An example of what I mean is that the quoted figures for the FQ400 are 387lbft at 1.3bar, which gives it a PI of 645, but the boost at peak power might only be 1bar, which would give it a PI of 742.

Quite a wide range as yuo can see.

Which should be the more relevant boost figure to use? Perhaps an average of the two? That would give the FQ400 a MAP of 2.15bar and a PI of 690...

Edited by Kozy on Wednesday 23 October 13:09