How Did I Achieve 252rwkw At Just 8psi?

[DRFT 14]

Hey Guys

I recently got my car dyno tuned. It made 252rwkw with an 8psi spring in the wastegate and no boost controller. Mods are: -

NEO RB25DET

Masterpower T3/T4

Custom Top Mount Manifold w/ 38mm Wastegate (8psi spring)

LinkPlus Computer

3inch turbo back exhaust

600x300x100 IC and 2 1/2inch piping

Walbro Fuel Pump

Sard FPR

I was just reading the "RB25 Dyno Results" thread and noticed that alot of people with similar setups required close to twice the amount of boost that im running to make the 250rwkw range. Another interesting factor about my result is that it was achieved with standard injectors. I remember posting on these forums before the tune and everybody said I wont make more than 220rwkw. Well, my 252rwkw was achieved at around 85% duty cycle.

Can anyone shed some light on the boost factor? What was it about my setup that managed to achieve 252rwkw at such low boost? I really found this baffling after reading the dyno thread.

I should also add that im really happy with the way the Masterpower turbo ended up performing. On one of my old threads. almost everybody told me to get a "turbo that wasn't from the stone age" and recommended a ball bearing turbo. Cant argue with 252rwkw at 8psi for the price of this turbo!

Edited August 9, 2007 by DRFT 14

[r33_racer]

you in america or australia?

[DRFT 14]

New Zealand

[shanef]

New Zealand

were the roads wet when this measurement was taken?

caus everyone know's wet roads = liquid horsepower for kiwi's

[RBwhatever]

Sounds a bit funny. 252rwkw on standard injectors running at 85% inj duty cycle. Doesn't sound right.

Are you sure they're standard?

[r33_racer]

okedoke...weird. I know most american results are abit higher then ours. Generally dyno specific as to why that happens.

[bazr33]

is it possible (even though the wastegate has a 8psi spring) that it could be running a higher psi?

cause i remember on my internal wastegated stock turbo i could run 16psi on the standard 7 psi spring.

[WARLORD]

could be a happy dyno ive see many in sydney.

[DRFT 14]

Highly unlikely that its running that high. Ive got a boost gauge, plus the tuner would have noticed. The tuner did say that it creeps up to 10psi at the top of 4th gear, but ive had a friend monitor the boost gauge while i was driving and it didnt budge past 8psi.

It doesnt really bother me. Im really happy with the results, just really curious as to why others require 16 or so psi to run the same numbers.

As for the dyno, a friend with an RB20DET and RB25 turbo upgrade (and all other related mods) only achieved 150 or so rwkw on the very same dyno, which he was disappointed with.So the dyno shouldn't be that happy I would think.

Edited August 9, 2007 by DRFT 14

[1jzDRFT]

is it possible (even though the wastegate has a 8psi spring) that it could be running a higher psi?

cause i remember on my internal wastegated stock turbo i could run 16psi on the standard 7 psi spring.

did you have a boost controller? what setting was the controoller set troo?

[redevil]

man anything is possible when you play with dyno's

[Guilt-Toy]

i was told from a few different people that stock injectors can get up to 250rwkw. i just never seen it before

i got 240rwkw from stock injectors before and i had a crappy fuel pump (walbro) with a decent pump and reg at a high pressure im sure it is do-able. (and a happy dyno of course)

Edited August 9, 2007 by Guilt-Toy

[InterCooL]

Im really happy with the results, just really curious as to why others require 16 or so psi to run the same numbers.

power isn't relative to pressure alone. its because you have a larger turbo, flowing more air for the same pressure.

if you get any turbo car and then replace the stock turbo with a bigger aftermarket unit, you will see a lot more power at lower pressures

[Lithium]

NEO RB25DET

Masterpower T3/T4

Good to see how the Masterpower turbo behaves. The reason for the high reading is Dynapack hub dynos read higher than the world famously low reading Dyno Dynamics dynos. Dynojef and Dynapack dynos (which outnumber the Dyno Dynamics which are rarely used out of Oz) read ~10-15% higher on average it seems.

I made 274rwkw @ 15psi at only 6000rpm before we stopped the tune on my R33 on Speedtech's hub dyno... power was climbing steeply there.

I run a GT3076R with a stock RB25 with Nismo 555cc injectors, and walbro pump.

[sh@un]

power isn't relative to pressure alone. its because you have a larger turbo, flowing more air for the same pressure.

if you get any turbo car and then replace the stock turbo with a bigger aftermarket unit, you will see a lot more power at lower pressures

spot on

look at Champ cars- mega power on about 3psi boost, big turbos and huge revs

[craked]

Good to see how the Masterpower turbo behaves. The reason for the high reading is Dynapack hub dynos read higher than the world famously low reading Dyno Dynamics dynos. Dynojef and Dynapack dynos (which outnumber the Dyno Dynamics which are rarely used out of Oz) read ~10-15% higher on average it seems.

I made 274rwkw @ 15psi at only 6000rpm before we stopped the tune on my R33 on Speedtech's hub dyno... power was climbing steeply there.

I run a GT3076R with a stock RB25 with Nismo 555cc injectors, and walbro pump.

im with you, i have played with a few dynos in my time hub dynos always read high and any dyno can be played with to show more power to make a happy customer

[R31Nismoid]

okedoke...weird. I know most american results are abit higher then ours. Generally dyno specific as to why that happens.

Same thing i was thinking!

DRFT - is it a hub dyno? If so, thats where it lies. They read a lot higher than a roller.

We had a good example a while ago where someone made 450rwkw, and ran i think 128mph and "neglected" to tell us it was a hub dyno and hence when you pull the figure back to around 370rwkw - the mph matched the power much better as "hubs" is not Rear Wheels, totally different

So realistically your probably sitting ~200-210wkw i would imagine, no more than that

[Lithium]

We had a good example a while ago where someone made 450rwkw, and ran i think 128mph and "neglected" to tell us it was a hub dyno and hence when you pull the figure back to around 370rwkw - the mph matched the power much better as "hubs" is not Rear Wheels, totally different

So realistically your probably sitting ~200-210wkw i would imagine, no more than that

It is a hub dyno - as has been covered. He's clearly making >250rwkw, if he was making 200-210rwkw thats what the readout would have said. Its all relative, the dyno is a tuning tool etc etc etc. So, on that dyno - realistically he is making 250rwkw.

Dyno Dynamics is somewhat of a minority in terms of the dyno results I've seen around the world, only contended by Mustang dynos in terms of low reading - so I don't think you can really say his reading is wrong Dynapack hub dynos and Dynojet rollers seem to have some degree of parity between them.

[Adriano]

It is a hub dyno - as has been covered. He's clearly making >250rwkw, if he was making 200-210rwkw thats what the readout would have said. Its all relative, the dyno is a tuning tool etc etc etc. So, on that dyno - realistically he is making 250rwkw.

Dyno Dynamics is somewhat of a minority in terms of the dyno results I've seen around the world, only contended by Mustang dynos in terms of low reading - so I don't think you can really say his reading is wrong Dynapack hub dynos and Dynojet rollers seem to have some degree of parity between them.

BUt the moroso calculator doesnt lie, MPH and mass tell it all. Why not take it to the drags, measure the weight, thats the sure way to know how much power it has. By the shape of the power curve, i would agree with nismoid, if it was making 250rwkw on 8 psi then the boost threashold would be higher with a different shape curve.

[R31Nismoid]

Its not wrong.

To claim rwkw is the wrong part