SR20DET 72 240z build

[Leon]

Just to revisit this.. check out this picture of the Rocky Auto front end. And if you know Rocky Auto they are S30 geniuses. They have a wide open front end.

 

 

Whole article:

http://www.speedhunters.com/2012/05/old-meets-new-rocky-autos-rb30-powered-fairlady-z/

Ok... read the article. Nothing in there about aerodynamics and its effects on cooling and lift, I didn't spot anything technical at all really. Just because someone did it, doesn't make it "right", no matter who that someone is. That would be like just taking someone's word for it instead of critically thinking about it for yourself.

 

I suppose you can say that it works, if your definition of "works" is that it runs and drives on the street. However, this definition (or specification) is application specific. From what I see, you're building more of a track car. The one in the article is, for all intents and purposes, a show car. Maybe a definition of "works" for you would be that temps don't excessively climb during a 30min track session and front lift is as low as possible. Maybe not, the specifications are up to you.

 

I'm simply making suggestions and giving some constructive criticism, take it for what it's worth. I would just advise you to read the Aero section of this forum as well as threads pertaining to venting and preventing excessive underhood air pressure. If you want some anecdotal evidence, then I'd ask you why is it that everyone else seeks to block the front end off, when building the Z for tracking or even land speed record runs?

 

I'm not even sure what the problem was before, exactly. You said you don't want to boil your fluids. Is that what happened last time? Were you using fresh, high-temp brake fluid? What cooling problems did you have before that you're trying to relieve now?

 

Sorry if this has been covered in your thread, but I don't have time to read through however-many pages of posts just to make sure that I didn't miss anything.

[SleeperZ]

Just to revisit this.. check out this picture of the Rocky Auto front end. And if you know Rocky Auto they are S30 geniuses. They have a wide open front end.

I don't think I am the only one confused by this. In general, if you restrict the air flow so it passes only through the radiator you get better cooling. If you leave areas open, air bypasses the radiator and reduces the cooling.

[Leon]

I don't think I am the only one confused by this. In general, if you restrict the air flow so it passes only through the radiator you get better cooling. If you leave areas open, air bypasses the radiator and reduces the cooling.

Precisely...

[itzgoten]

And how would you cool down the engine bay then? I feel like you're generally saying headlight ducts would make the car worse because essentially that is what I am going after.

 

What I'm getting at was the bay was very hot. I wanted to open up more. I am not concerned with cooling down my radiator because that is what the fans are for. They are high CFM fans and literally bring down 10 degrees in less than 30-45 seconds. The fan would turn on momentarily and turn off right away. As far as the intercooler. It sit in front of the radiator support. So I don't see how that would affect anything I'm doing.

 

I ran fresh RBF600 fluid but the turbo and manifold are inches away from the BMC. I understand the general concept of forcing the air the pass through the FMIC and to the radiator and I do agree with you. But in my case I disagree. And from your comment I felt that you do not know what I did or where I was coming from. Hence disagreeing with you. My intake are temp is fair and the intercooler is going it's job. However I feel that getting air behind the radiator to the intake would benefit as well.

 

Either way. I'm boxing the front and one side will have an oil cooler and the other side is going to have a duct pointing to the intake.

Edited May 12, 2012 by itzgoten

[SleeperZ]

Cooling the radiator is the most efficient use of the air flow. Keep the radiator cooler and you keep the rest of the engine and bay cooler.

[itzgoten]

(I'm typing this on my iPhone so please bare with me)

 

I see your point but if my turbo & manifold is creating a lot of heat in the engine bay how does this relate? Cutting those holes to cool my engine bay is the same affect (to me) like getting the turn signal intake ducts and pop up headlight ducts on my miata. My miata runs cooler and feels more responsive. It's valid because the spec miata guys do this too. They run no turn signals to get more air. So how is this any different? I know where you are coming from but I feel what I'm doing is similar to that effect.

[Six_Shooter]

The difference between what people do in a Miata and what you're doing in your S30, is that the design of the front still forces air through the radiator in the Miata, using the headlight buckets provides an alternate route, in a different part of the air flow over the car, for air to get into the engine bay at a very different location.

 

The idea of creating air dam(s) around the rad to force more air through the rad, doesn't just apply to the S30, but all cars on the road. This is one reason that you will see those small air dams under the rad support on many cars, especially '80s GM cars. It was used to create a low pressure air behind the rad to force the high pressure air in front of the rad through it.

 

As far as turbo adding engine bay heat is concerned, using a turbo blanket or ceramic coatings are MUCH more effective at keeping engine bay temps down than to try and use air flow to cool the engine bay. The air passing through the rad will still be cooler than the heat coming off the turbine housing and exhaust manifold, so the air through the rad will still be effective at cooling the engine bay.

 

I still think I'd worry more about getting the air out of the engine bay and less on getting air into the engine bay. Creating a way to evacuate the air more efficiently will create a way for more air to flow through the engine bay.

[itzgoten]

The idea of creating air dam(s) around the rad to force more air through the rad, doesn't just apply to the S30, but all cars on the road. This is one reason that you will see those small air dams under the rad support on many cars, especially '80s GM cars. It was used to create a low pressure air behind the rad to force the high pressure air in front of the rad through it.

 

As far as turbo adding engine bay heat is concerned, using a turbo blanket or ceramic coatings are MUCH more effective at keeping engine bay temps down than to try and use air flow to cool the engine bay. The air passing through the rad will still be cooler than the heat coming off the turbine housing and exhaust manifold, so the air through the rad will still be effective at cooling the engine bay.

 

I still think I'd worry more about getting the air out of the engine bay and less on getting air into the engine bay. Creating a way to evacuate the air more efficiently will create a way for more air to flow through the engine bay.

 

Again, I am not worried about cooling down the rad because I am already cooling it down enough. I'm still going to box the intercooler and radiator.

 

I already ceramic coated all of the exhaust parts with a turbo blanket. It frustrates me when people are going to join the conversation and tell me what they think when they have not see what I've done so far. It's nice of you to read the last page and chime in but if you were to cretique me, at least know what I've done and where I'm going with this.

 

The finished product will have a duct on the passenger side to the intake, the right side will have my oil cooler and the middle will be blocked off so air is forced through the intercooler and radiator. Holes were drilled on the where the BMC was and the battery tray. BJHines did the same thing and told me with his windtunnel tests it showed that cutting the hood (low air pressure zone) is not as effective as cutting out the sides (high pressure zone). So I took his advice and that is what I did.

 

But for everyone to say I'm doing it wrong. Show me you've done otherwise and I can see. This shows you're credible because you've applied it. But it easy for someone else (not you specifically) who, for example, owns a mildly stock car and only reads things online to come tell me I did it wrong. I'd rather trust sources who've been in the business and have done it a certain way than to trust someone who's only interested in proving a point when they have nothing to show for it. Again, I'm not referring to anyone here but in general that is how I feel. Like someone going up to a drag racer doing 9's and telling him his build is all wrong and they don't even have a car worthy of mentioning.

Edited May 12, 2012 by itzgoten

[Leon]

You're free to do what you want, no one's stopping you. We're providing constructive criticism besides the typical "he said, she said." We're talking physics, not what one person or the other has done. Obviously it's your car, so you can do as you please.

[Six_Shooter]

It's nice when people assume that others have not followed along from the beginning. /sarcasm

[SleeperZ]

@itzgoten -- I only posted my thoughts on the subject because you invited them. You are not being criticized, in fact I love your build, and I have followed it from the beginning as have most of us.

 

Six_Shooter is right about exhaust coatings being more effective at keeping temperatures down, especially combined with the low pressure in the engine bay keeping the airflow up to carry the heat out. Bypassing the radiator will decrease your overall cooling.

[itzgoten]

Six_Shooter is right about exhaust coatings being more effective at keeping temperatures down, especially combined with the low pressure in the engine bay keeping the airflow up to carry the heat out. Bypassing the radiator will decrease your overall cooling.

 

So this goes back to the original issue. You are saying that with my intake behind the radiator as it is now. I can bring down the intake are temp but just ducting the radiator and not making a seperate duct for the intake itself.

 

And I assume the build is not being followed because I already had the parts coated. If you go back and look. The exhaust side of the turbo, the turbo manifold, dump tubes and down pipe were all coated. I also have a turbo blanket for the turbo too and after T-Hill it was still too hot.

 

There was also a guy who replied on here wth his oil cooler install and had his radiator support was modified and he only had a bar across the top for support.

 

Either way I've said this like 3 times arleady. The front FMIC and RAD is being boxed to force air through it anyway. We're just going in circles.

[Six_Shooter]

What do you consider "too hot?" Are parts melting? What are the engine temps at this point of "too hot of an engine bay?" You may be solving a problem that doesn't exist.

 

The other thing that is as important to keeping engine temps down as cooling is the tune. I've reduced engine temps on my own cars by as much as 30 degrees under the same conditions with a good tune, making more power and better power bands to boot.

Edited May 12, 2012 by Six_Shooter

[gearheadstik]

Love the car, but is it just me or does the rear flare look like its on the wrong side?.. The shape just looks a little off.

[Gollum]

itz ~ it sounds like you've gotten good advice from people who HAVE done it, like bjhines, but it seems like you still haven't gone and done your research in the aero thread. That section of the forum was opened up because people HERE actually banned together to get windtunnel time and tested many popular configurations to see what the real results are.

 

If you were having bay temp issues despite the turbo blanket and coatings then your bay is still at a very high pressure. The issue isn't getting air in, but getting air out in an efficient way. The tests also concluded that ANY air bypassing the radiator into the bay led to increased front end lift.

 

I know I'm "just some guy on the internet" but I'd be willing to bet that rocky auto's top speed isn't any better, if not WORSE than a completely stock 240Z with 300hp.

 

Go check out the numbers. By doing the front end right you can go from having quite severe front end lift to front end downforce. And more than anything else the testing showed that there was no magic bullett but that you need to have a SYSTEM approach. Treating just the front or the back is a waste of time. Doing either hap-hazard is just working against you as well. Which is why people here are being very vocal about trying to help you out. We don't want to see you cutting up your front end just to end up being worse off in the grand scheme of things. Even if you've brought bay temps down by 50 degrees is it worth it if you've pulled your top speed down by 20mph?

 

Also, as mentioned just a few posts ago, what bay temps were "too high"? I've seen plenty of OEM bays that get outrageously hot under track conditions. As long as the fluid temps stay manageable I don't really see the issue in this regard. Use a turbo timer or just make sure you never shut down right after a run and you should be fine. Keep water and oil temps within a happy zone and call it good as long as you're not melting things in the engine bay.

[itzgoten]

Love the car, but is it just me or does the rear flare look like its on the wrong side?.. The shape just looks a little off.

 

gearheadstik - Thanks. But I have no idea.. looks fine to me. But at this point I'm not making anymore holes. ::shrug:: What can we do now? Hah

 

I know I'm "just some guy on the internet" but I'd be willing to bet that rocky auto's top speed isn't any better, if not WORSE than a completely stock 240Z with 300hp.

 

Even if you've brought bay temps down by 50 degrees is it worth it if you've pulled your top speed down by 20mph?

 

Also, as mentioned just a few posts ago, what bay temps were "too high"? I've seen plenty of OEM bays that get outrageously hot under track conditions. As long as the fluid temps stay manageable I don't really see the issue in this regard. Use a turbo timer or just make sure you never shut down right after a run and you should be fine. Keep water and oil temps within a happy zone and call it good as long as you're not melting things in the engine bay.

 

Gollum, I would disagree with you about the Rocky Auto car but to each their own. My style of building is like them and I concur with their build style. If it's wrong then so be it. I'm not trying to do 200mph. I'll probably hit 150mph at best. I did not do something irreversible so I will cover up what's left of the holes if I do not get the results I want. The front will seriously have a huge vent pushing air through the FMIC and to the rad. The small slits on the side will have air for my 19 row oil cooler (which will fill up the entire space if not more) and duct to the intake. If I seriously get lift that is THAT bad I can cover them.

 

Which leads me to the next comment. For ME I'd take take -50deg over 20mph and I can care less.. I have the power and will make plenty more. But if heat is my concern I am going to attack that first and learn from there. I completely understand where everyone is coming from with buttoning up the front. But if this were a newer car I would have bought a headlight air duct. To the same affect I made some holes which I felt were needed. 10 more guys can jump on here and tell me I'm doing it wrong but hey, it's my build. I get your point but I don't think you are getting mine. So with that said I'll do it my way and thanks for the advice.

 

And your last question. The exhaust area was hot enough to warp my V-Band for the exhaust. The screw became warped and I had to saw off the bolt and pry off the v-band. It was unusable just after 30 minutes of very hard driving. With that evidence I assumed I've reached some critical temps in my bay. I had a heat wrap over my BMC and I think that was able to save me from boiling fluids but I didn't have any temp readings at the track. The holes can be easily cover in seconds and I'm doing this to see if my next visit to T-Hill will sing a different tune.

Edited May 15, 2012 by itzgoten

[SleeperZ]

...

 

And your last question. The exhaust area was hot enough to warp my V-Band for the exhaust. The screw became warped and I had to saw off the bolt and pry off the v-band. It was unusable just after 30 minutes of very hard driving. With that evidence I assumed I've reached some critical temps in my bay. I had a heat wrap over my BMC and I think that was able to save me from boiling fluids but I didn't have any temp readings at the track. The holes can be easily cover in seconds and I'm doing this to see if my next visit to T-Hill will sing a different tune.

Yes, you do have a heat issue, and it's good you are keeping your options open. But if your exhaust components themselves are overheating, a bit more air over them is probably not going to save them. I don't want to make any more assumptions than I already have, but it sounds like your EGT may be a bit too high.

[itzgoten]

The shakedown at T-hill will prove or disprove my theory. But i will close up any unused holes.

[VKLR]

I learned from RC electric pylon racing how to cool a 4Kw electric motor and not paying a penalty doing so. Use very small inlets and larger outlets. You want to create a vacuum, not force air in there. Forcing air creates lift and drag.

[itzgoten]

I learned from RC electric pylon racing how to cool a 4Kw electric motor and not paying a penalty doing so. Use very small inlets and larger outlets. You want to create a vacuum, not force air in there. Forcing air creates lift and drag.

 

 

Agreed. I don't feel the holes I made were too big and I made holes on the side to vent. But what you are saying makes sense. I don't plan on having a huge hole up front. Just playing with some ideas right now and we'll see how it goes.