Small vs mild vs large streetport

[vex]

Originally Posted by RICE RACING

Further to this post (stock V's street port)

Two RX7's both weight checked prior to running, both dyno's *varying methods* alone with vastly varying estimates of engine power! one matches reality (read other cars) the other is optimistic to say the least!

Stripped track car (13B-REW street port) Garrett single turbo 1.3bar
1> 1180kg (432rwhp DD! owners dyno shop estimates 509bhp!!!!!!!)
100kmh-200kmh = 8.3 seconds

Road car (13B-REW stock) Garrett single turbo 1.3bar
2> 1380kg (275rwkw "real power measure!" owner estimates honest 430bhp in this test)
100kmh-200kmh = 8.2 seconds

(same number of gearshifts, same OEM gearbox, same shift points.........) *both at sea level and std temp and pressure day* You do the maths power curve on one is far superior, but also some dyno figures are not worth the paper they are printed on

Unless those dyno's are certified accurate and the paper they print out shows not only the peak power and torque, but everything else such as the torque curve and what not.

[RICE RACING]

Any dyno can certify what ever it likes @ the end of the day. I see sheets from all over the world from all types and most of them count for shit in my books, especially when you see what kind of "factors" people slap on to estimate the engine power.

Best Reference you can have is reality.

It's commonly available to almost anyone hundreds of cars (legitimate ones) from OEM sports car makers and you can find at least a dozen well known cars in your class all of which have been tested on proper electronic scales before the test, along with the OEM engine dyno rating and low and behold some "500rwhp" 300kg less Mazda's with hektik power bands still can match the figures of much less specified cars running normal manual syncromesh H pattern shift conventional gearboxes

Most if not all the figures you see from performance shops are BS, most of the engine "enhancements" especially to do with porting are a liability rather than any type of asset, making the cars louder, and much more peaky as well, all for the sake of making the same power on 1 or 2 psi less peak boost and 600rpm higher engine speed............ problem they all forget is you loose out so much mid range and upper end power before your normal red line of 8k. A stock ported 13B-REW even when fitted with a full catalyst exhaust will make usable power to 8k rpm, unlike its ported cousins it will make a shit load more power in the mid range and upper revs especially 5k to 6k rpm (where you spend a bulk of your time).

It's a great question, one lots don't really give much thought or proper on road/track analysis.

[vex]

Originally Posted by RICE RACING

Any dyno can certify what ever it likes @ the end of the day. I see sheets from all over the world from all types and most of them count for shit in my books, especially when you see what kind of "factors" people slap on to estimate the engine power.

Maybe I should have qualified that statement? I'm used to certificates of accuracy being given for instruments such as pressure transducers, thermocouples, etc, etc. The one's that usually cost a good 12k+ to get certified with a %error of +/- 0.01% (exaggerated, but you get the point).

Best Reference you can have is reality.

I think the best reference you can have is a statistical analysis of other cars based on specific dyno's. You can have multiple readings from the same car but different effects on the engine resulting in large discrepancies of the car. If the effects of the run time and environment can be accounted for the statistical analysis can give a more realistic understanding of the car's power profile.

It's commonly available to almost anyone hundreds of cars (legitimate ones) from OEM sports car makers and you can find at least a dozen well known cars in your class all of which have been tested on proper electronic scales before the test, along with the OEM engine dyno rating and low and behold some "500rwhp" 300kg less Mazda's with hektik power bands still can match the figures of much less specified cars running normal manual syncromesh H pattern shift conventional gearboxes

Agreed.

Most if not all the figures you see from performance shops are BS, most of the engine "enhancements" especially to do with porting are a liability rather than any type of asset, making the cars louder, and much more peaky as well, all for the sake of making the same power on 1 or 2 psi less peak boost and 600rpm higher engine speed............ problem they all forget is you loose out so much mid range and upper end power before your normal red line of 8k. A stock ported 13B-REW even when fitted with a full catalyst exhaust will make usable power to 8k rpm, unlike its ported cousins it will make a shit load more power in the mid range and upper revs especially 5k to 6k rpm (where you spend a bulk of your time).

Of course. There's a bunch of trade-offs when it comes to porting, but at the end of the day you need to know how much air is going through your system and what velocity you want that air to hit the combustion surface.

It's a great question, one lots don't really give much thought or proper on road/track analysis.