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My thoughts on 'big' power


Dommo

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1 hour ago, Andrew said:

Much better wringing the neck of 170bhp. 😉

You know what - I like that sentiment. 😁

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3 hours ago, Mole said:

 Interesting...

What are the two temperatures on the graph..? And where were the sensors?

 

The red is coolant, peaking just under 96, lowest mid 92. That's as measured at the thermostat, so leaving the engine.

Blue is intake temperatures, just before the throttle body so after the intercooler. That's in the 32~36 range

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1 hour ago, Andrew said:

 

Back to the OP. Rotary engines are usually pretty loud.. will need some serious silencing for trackdays?

 

It will definitely need more than I run now, but shouldn't be too bad. The RX8 has the exhaust ports on the sides rather than the face... if you squint you can see in this picture:

 

rotary.gif

 

It's not such a straight route out, which doesn't help for power or heat unfortunately!

 

Can always be a massive hypocrite and quieten it down with a turbo, right?

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12 minutes ago, Dommo said:

 

The red is coolant, peaking just under 96, lowest mid 92. That's as measured at the thermostat, so leaving the engine.

Blue is intake temperatures, just before the throttle body so after the intercooler. That's in the 32~36 range

Ok thanks.. and what about oil temp?

You have done well with the temps..

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.I've always had a soft spot for a w**kle I had a neighbour growing up who had a brand new NSU RO80 it looked sounded and drove like a space ship, well that was in the early 1970's.

I think it's a great engine for a Westfield. I also run a high powered Mazda SDV with similar power output as your car, I'm not a track day star I use it for fast road mainly it has duel boost control so I can potter around at 250bhp then throw a switch and I'm over 300bhp it's a pleasure to drive but requires respect like any high powered car.

My ideal would he turbo mx5 for the road and a BEC for the track.

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2 hours ago, Mole said:

Ok thanks.. and what about oil temp?

You have done well with the temps..

 

I must admit I never did get around to fitting the oil temperature sender - still sat on a shelf in the garage! I ran out of room with the take off I purchased and that's pretty much where it ended. Pressures were fine, there were no ill effects so until you just mentioned it, I forgot I even had it. I bet I'd have bought another sender for the RX-8 engine too 😄

 

Oil was cooled with a mocal 13 row effort. I had plans to fit a laminova and dump the oil heat into the coolant to simplify the pipework a bit but couldn't find a happy place for it. Oil was on one side of the engine bay, coolant on the other.

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@Dommo - We must compare the inlets to our nose cones, as I have been pondering why your cooling is so good with no ducting.  Whereas mine ceases to function  from 70-80mph onwards without the ducting.  I forget name for the style of integrated nose and bonnet you have, I am just curious if your spot on cooling with stop being spot on if you have to move to a conventional nose and V8 bonnet to fit the rotary.  One to consider :)

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It's an FW bonnet.

 

Though I doubt it's that alone, (maybe the different top vents help somehow), FW noses have proven just as susceptible to the rad bypass issues as others. It's more likely to be something in the mapping I suspect.

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5 minutes ago, Dave Eastwood (Gadgetman) - Club Secretary said:

It's an FW bonnet.

 

Though I doubt it's that alone, (maybe the different top vents help somehow), FW noses have proven just as susceptible to the rad bypass issues as others. It's more likely to be something in the mapping I suspect.

 

But the mapping would not affect the airflow issue at high speed, while it could be used to keep combustion chamber temperatures down a touch you still have many horsepowers worth of heat to get rid of through the radiator.  There is definitely something to do with Dommos set up that somehow makes efficient use of the airflow through the radiator, be that the intercooler being forward enough to capture the airflow before it can run away, as a duct does, or something else.  We have been at the same track days in near 30 degree temperatures and his just works, and this is before he ducted side (have you fitted the other side yet?).  If we could crack what this is it could be of use to other members.  We need @maurici to comment 😃

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43 minutes ago, the stoat said:

 

But the mapping would not affect the airflow issue at high speed, while it could be used to keep combustion chamber temperatures down a touch you still have many horsepowers worth of heat to get rid of through the radiator.  There is definitely something to do with Dommos set up that somehow makes efficient use of the airflow through the radiator, be that the intercooler being forward enough to capture the airflow before it can run away, as a duct does, or something else.  We have been at the same track days in near 30 degree temperatures and his just works, and this is before he ducted side (have you fitted the other side yet?).  If we could crack what this is it could be of use to other members.  We need @maurici to comment 😃

 

And the answer is back pressure inmediatly behind the rad. (and this does not necesairly means actuall stuff behind it)... is basically a pressure balance.

I found that with my former westfield.

 

Behind the radiator was not many things... and in the sides, it was quite a lot of stuff... (Dry sump pump, massive manifolds...) so apparently there was not an obvious baypass route, and the air was still going trough my radiator quite nicelly. I had no ducting in the front, and I usually had overcooling problems...

 

In my former MK, despite the engine bay was significantly emptier (r1 BEC engine) and I had ducted the nose to the rad to avoid air leaks, this was still not working very well, and didn´t work well untill I managed to lower the air pressure inside the engine bay ducting the radiator outlet somewere with obvious air escape.

This is more an Aero thing than actual cooling. I find myself pretty often simulating (well... requesting simulations, I don´t run them) several times front end layouts with minimal ducting changes and minimal layout changes with a massive impact in drag and aero... and sometimes we do pretty big changes expecting massive improvements only to do nothing.

 

In the case of a westfield... and taking in account all is budget build... it is difficult to predict.

 

When I got my former XE car, with that much power and a not that big of a radiator I expected to work very poorly and I thought @AdamR was nuts when he did the setup, only to prove myself really really wrong. well, he is nuts but the car including the cooling system was spot on (is the only car I have never ever modified the cooling system).

 

Trial error is the thing here. IF (really big IF....) you are sure the heat rejection of your rad is just good enough (because someone runs the same setup and works) but you are not cooling, chances are you have an airflow problem. Ducting, unducting, and allowing air out from the engine bay are solutions you can try, however, generally, a nicely ducted nose and an engine bay with flared sides, or slotted bonnet in the back, should work in most situations.

 

 

 

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In fact this is the reason for some of my questions..to get rid of so much heat probably 30 percent of the power through the various coolers I was interested how it was done.. 

Details on radiator size and other info would be good for those of us that struggle with heat when on track..

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The bit I find most impressive is how the radiator can ditch the heat after the intercooler has done its work. My intake temps are cooler than when I had throttle bodies, yet the air coming out of the turbo must be ridiculously hot at 21psi?

 

I suppose one saving grace is you never make that much power for that long, plenty of time to dissipate heat whilst braking and cornering.

 

The radiator/intercooler combo is a radtec unit, originally created for the Corsa engine'd Sport Turbo's Westfield sold as their type approved vehicle. Other than that it's a very simple coolant route with OEM waterpump and OEM thermostat. No ducting... also no front grill. That seems to make a difference to some cars (I've never run it since if fell off in 2013).

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  • 2 years later...
On 21/05/2020 at 18:45, Mole said:

Russ...

Well like many have said before I think there is a sweet spot on a Westfield for power.. and maybe a naturally aspirated engine feels natural to me.. I think having 280 - 320 bhp would be a nice sweet spot... Especially for track use..

When you get yours back on track I look forward to seeing if that is correct!

What do you think..better with less?

 

On 21/05/2020 at 18:58, TAFKARM said:

 

220-250, but I’m a better driver than you. 
 

Definitely more than 190. 

I have a Zetec Turbo with controllable boost from the cabin. I have a choice of 4 settings starting at 210 and going up to 272. For me level 2 is the sweet spot, it's perfect at 228. Occasionally I use level 3 but 99% of the time I'm driving at 228. Don't forget weight comes into to equation too in my opinion. My Westie is quite heavy, about 670kgs with a full tank and I'm not a small bloke. A 600kgs car with a 10 stone bloke in it would be another story, 228 would no longer be the sweet spot. Then of course there is driver skill and brave pills! I have a friend with a 160bhp Caterham, he can keep up with a 420R on the road no probs. He is an ex race driver though! 

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