RotorMotorDriver

iTrader: (1)

Good call BTW Paul.

~T.J.

Winnipeg85GSL

I'm sorry but with a T76 one would expect more HP. A good start though. I'm N/A and got 220

gamble302

winnepeg youve got a bp dont you? thats to be expected haha

dowelled? from what ive read dowelling is just a band aid for poor tuning. im no expert, im just regurgitating what ive read as i understand it. was a post on the aussy forum if you feel like searchin for it

gamble

PaulFitzwarryne

Gamble. Dowelling is a well engineered modification to hold the engine components together when you are generating substantial power. Once you are above about 300 hp then its essential even when the engine is well tuned.

Extreme bad tuning, wrong air/fuel ratios, will generally cause major damage to internal components such as apex seals even if you are generating low power. Dowelling will not help you. One bang and you can be dead!

PaulFitzwarryne

Winnipeg- each turbo has a maximum potential but whether this is acheived depends on other components. More boost will obviously give you more power. It also gives you more heat

Is the intercooler big enough to cope?
Will the plumbing stand the pressure?
Is the carb big enough to provide the fuel, with efi are the injectors large enough, what has happened to the Air/Fuel ratio?
Will the internals stand the increased pressure? Will the seals hold up? Will the engine fall apart in a dramatic fashion?
Will the clutch, driveshaft, and diff stand the extra?
stress?

Its like a pyramid of cheerleaders, one weakness no matter how attractive, and they all come tumbling down!

RotorMotorDriver

iTrader: (1)

I think Winnipeg85GSL has a 302 in his car guys .

~T.J.

Winnipeg85GSL

I was kinda kidding, I'd rather not start another arguement. I'm actually quite impessed with those numbers for a 12A.

gamble302

he doesnt have a GAMBLE 302 in his though :P

yes ive read the dowelling is a great mod, but also that it isnt needed if you are properly tuned. do you have any links to more info on dowelling i could read up on? i really would like to know more about it

gamble

mperformance

I've heard dowelling is unnecessary...

PaulFitzwarryne

It would be interesting to know who says dowelling is not necessary. Top builders in Aus such as Dalton, Dyson ond Rotorworx all recommend dowelling for high performance motors.

Even top street machines use dowelling, but then we are talking over 500 rwhp@26 boost for 10 second 1/4 mile times. Once you get to 8 second RX-7s with a full race engine, dowelling is essential if you want to last the full 1/4 mile!

As a matter of interest the street set up I am considering is a "Stage 3" with four 12at injectors which will get me high 10 second runs on a 2600 lb RX-7[full street trim]. On a drive in-drive out basis it will cost about $12,500 with a rebuild. If I wanted a stronger driveshaft, diff and gearbox then the budget would be higher. Unfortunately the RX-7 parts are a bit fragile even for street use, and a Supra turbo box and HiLux diff are good options if the money allows.

If you are only playing with under 300 rwhp in a daily driver then dowelling is not so necessary.

HeffBoost

Here Here

pillage6

Well, I have a 13B, so base your numbers on that.

I am playing with a MBC right now, pretty scary how quickly the boost changes with just a little turn of the ****.

pillage6

He made it a point to tell me that the back side housing was from a 91, he said the 87 engines had a problem with cracking?

Was he smoking crack? Or selling me some bullsh!t?

mperformance

ok Paul you cleared that up.

Is there a difference between the 12a and 13b in terms of the dowelling issue?
I also heard that 12a need no dowelling up to a much higher HP figure than 13Bs

pillage6

Well, my goal is to hit the 12's.

pillage6

Robert at Rotaryshack.com is pushing 15psi. with no intercooler.

PaulFitzwarryne

pillage6- running 15psi without an intercooler will really increase the charge air temperature. The usual professional advice is to use an intercooler from 6lb boost, 8lb max. A good IC can add in the order of 20% more power safely for the same boost.

The problem with just winding up the boost is excessive heat which increases the chance of premature detination, one of the major causes of engine damage [knocking/pinging]

To get power without damage you need a tight balance of boost, the air/fuel ratio, air charge temperature and ignition timing.

With due respect to Robert and the very high power numbers he posts on this forum , using 15psi without an intercooler seems a strange configuration to optimise the way of getting power. While its cheaper and reduces turbo lag, the chances of self detonation and leaning out due to reduced oxygen vastly increase.

To go back to the specific purpose of this thread, OK increasing your boost will increase power towards the 200hp or more mark. But my warning is that without an intercooler the chances of engine damage increases unless you manage to get ignition timing and the A/F mixture just right. An alternative is water injection but few people now use that approach since IC technology became so good.

You can relatively safely put your boost up for a dyno shoot-out with everything under control but on the road its a different situation. One problem is fuel quality/ octanf levels vary so much depending where you pick it up.

PaulFitzwarryne

mperformance- like you I have heard the 12a engine has more strength reserve. To what extent there is no published data, one reason perhaps is that few people pushed up power on the 12a once the 13bt became available.

Looking up specs on the works race engines of the time is an eye opener. The 12a engine built by Racing Services of Twickenham for the UK Saloon Car Championship produced 190bhp. Even the 1981 Le Mans full race engine only produced 290bhp with a massive Mazda factory budget, The ouput of the IMSA cars of that period was only about 270 bhp in its NA format and 300bhp with efi. At that level of output dowelling is only a marginal option

Thus, 200 rwhp in a street car has to be put in historic prospective. Along comes turbo technology and you are in a different universe of options

REVHED

Rice Racing uses no dowelling in his 500hp, 300km/h monster.

PaulFitzwarryne

I was using the latest advice from Rotorworx who recommend 6 additional dowelling from 300-500rwhp and an additional 8 for above 500np. At a cost of $400-460 it sems woth while. when you have invested thousands in the engine

An example of dowelling by Rotorworx is Freeknu with 512rwhp@26psi, who achieved a 10.24 second run at the Adelaide nationals. Thats some going for a street car!

Its not that I am knocking Rice Racing, but I think a little safety is justified when the rebuild time is not free.