swoope

iTrader: (5)

ah,

back to hood venting.. very intuitive denny..

someone needs to ring the bell on that..

beers

joff

I did the DIY hood venting trick with removing the weatherstripping and propping up the back of the hood slightly a month or so ago. It seems for me there is no effect on intake temps. I also didn't notice anything with the DEI chill charge additive-- maybe I mixed too much. Going from parallel plumbing of the stock Pettit heat exchangers to series seems to have slightly worsened AIT. My prediction is that the biggest factors in AIT without meth is in our water pump flow rate and heat soak in our aluminum post-intercooler/pre AIT sensor piping.

On another note, I just bought my wife a '94 RX7 with a slightly upgraded engine (bridge ported, upgraded exhaust/intake/IC, stock twin turbos) and we were playing cat and mouse on the street and highway against our S/C 8 recently. The 7 is faster (currently set to 13 psi), but really only slightly. I was surprised just how well the S/C 8 could keep up when forays were limited to mostly street legal speeds. However, once the secondary turbo on the 7 kicks on in 3rd gear, the 7 really starts to pull away fast, but the noticeable lack of lag of the S/C compared to the 7 does make for some very close matchups depending on starting speed and gear.

marsredr100

iTrader: (1)

Corner balance/Autocross alignment

Can anyone recommend a good location (preferably from experience) in the greater Tampa-Lakeland-Orlando area that can perform this service?

olddragger

iTrader: (3)

i have been wondering about the series versus parallel plumbing---i had wondered why pettit did it that way. well it's summer and time for experiments. But one thing at the time. Temps will be hot today and I plan on seeing if the small stuff is helping any.
Venting the hood i think may help with heat soaking some--dont know--better help somewhere as i dont like smelling the engine when i use the a/c.
OD

marsredr100

iTrader: (1)

The reason why Cam ran the hoses that way (parallel) is to double the diameter flow of water thru the heat exchanger. The heat exchanger included in the kit is only 3/8” in/out diameter tubing. Therefore, you basically double that diameter to 6/8” or ¾” diameter. Otherwise by running the line from one heat exchanger to the other (in series) you will end up reducing the water flow (3/8” diameter in/out instead of ¾”).

marsredr100

iTrader: (1)

This is good only if the car is not moving but while driving the negative pressure crated over the hood will actually disrupt the intended front to rear airflow (under the bumper opening, thru the radiator and out bottom of engine bay). Last year while at Pettit I asked that question to Cam (removing the weather strip). He showed me a computer model diagram on the airflow effects on an RX8. It clearly showed (visually) the effects of wind resistance, airflow pattern and pressure points. In other words, don’t take the weathers strip off unless you are planning to sit on a parking lot.

marsredr100

iTrader: (1)

Must be the driver but regardless who’s driving either car, my money is on the wife hands down.

olddragger

iTrader: (3)

hooking the i/c hoses that way will do as you say but doesnt the actual completed volume of flow through the intercooler remain the same? Given a certain size of cooler the flow cannot be increased without increasing the pressure, but i do I admit i am learning here.
i also understand what the studies show on the airflow thing with the hood.
It does work with low speed/city. suburban driving. Getting to higher speeds say over 70mph and then the flow is more disrupted, but the affect is minimal. Not only do you remove the strip but you also slightly raise the back of the hood.
Do this--measure the temperature of the surface of say your fuse box top with a little laser temperature gun--then take the strip off(it comes off easily and you can put it back on easily) and elevate the back of your hood with the thing of your choice. Now do the same drive again and see what you find out.
OD

olddragger

iTrader: (3)

OK found my own answer----and what others have been TRYING to tell me!!!!!!!
The longer you keep the water in the ic's the better. If the flow is to fast and this is what hooking them up in series will do, the water does not have a chance to cool it as much. So the pettit way is the best way---as usual. Oh well I learn all the time I guess it is time to figure out how to hook them back up in parallel while keeping enough room to keep my rb intake duct.
Honey oh Honey can you take the front clip off for me AGAIN!
olddragger

MazdaManiac

iTrader: (3)

Lets not get this debate started again.
Its already been conclusively proven by more than a few people that removing the strip and slightly raising the back of the hood lowers engine bay temps under ALL conditions, regardless of speed.

marsredr100

iTrader: (1)

Yes, I agree with you but not on the RX8. See pixs below of my R100 raised hood. I don't have an undertray on it, therefore airflow and engine bay heat escapes thru the back of the hood gap. However, after watching the computer animation graphic it was very clear to me that the negative pressure created over the end of the hood area will actually draw air in from the back of the hood into the engine bay (unless you are running an aftermarket hood with vents on the top) BUT it will not allow proper airflow into the engine bay from the front of the car. On another note, I saw an RX8 at the dyno shop with no undertray. That is a big no-no. Regardless, I tried a while back removing the weather strip and did not see/noticed any engine or IAT temp drop. BTW Jeff your avatar collection needs a serious overhaul (too many repeats). In lieu to that I’m including an avatar for your new collection. Enjoy

MazdaManiac

iTrader: (3)

I don't care what the computer simulation says - that isn't how it actually works.
Reality trumps theory every time.

joff

Actually, my wife was driving the 7 during all this. I drove the 7 today. I no longer think our 8 is even close. I think she was shifting early and too slow and loosing all the boost. The FD really is stupid fast. My wife took one of her girl friends out for a drive with it today and the acceleration skipped right past "fun" and instead provoked genuine fear from her passenger.

Re: the whole vented hood -- for what its worth -- I didn't notice any difference good/bad in coolant temps either. I seem to always run a fairly typical 180-195 with and without hood venting. The software Pettit uses to analyze the aerodynamics sounds neat. Even if it only helps when stopped, I think I'll still keep the weatherstrip off as my coolant temps still are ok and I like the idea of better ventilation to deal with heat soak after parking.

california style

Juan, what would a proper vented hood do (ie a new hood with actual vent slots, rather than OEM with raised rear)? look pretty or achieve better temps?

Or is it an unknown?

marsredr100

iTrader: (1)

Nice! I like your wife already.

marsredr100

iTrader: (1)

A vented aftermarket hood allows engine bay heat to escape while at idle/slow speeds and at high speed it will draw the hot air out of the engine bay due to vacuum effect as long as the holes at not to close to the windshield where negative pressure develops at high speed.

olddragger

iTrader: (3)

well you see i agree about the negative pressure and all that but you have to admit that outside air will be going into the engine bay regardless of source, front or back, and there is no overheating going on to imply that the normal front to back flow is seriously disrupted.
We are speaking of cooling the engine bay--this will not have any effect on iat except maybe a little less heat soak.
The vented hood (father up front) is actually designed to help cool the radiator by letting the flow through the front clip /radiator have a faster escape AND therefore adverting that hot flow from the engine bay. In that manner it also helps cool the entire engine bay.
But we have factual measurements (like MM says)that the vent trick does lower engine bay temps without causing overheating issues. There are better more efficient ways for sure, but this works some. Before i installed the s.c. kit I did this and measured a 10 degree drop on the top of my coil packs.
By the way i diverted the out coolant hose away from the alternator and i did the hood trick. My iat's were much lower but I also was not running the a/c this time. Still the iat was only 18F above ambient of 87F. I think the humidity is a little less today, but that is the lowest difference between iat and ambient i have ever had (since the days have been above 80F). It is really hard to compare apples to apples this way.
olddragger

marsredr100

iTrader: (1)

OD

Here is what I did to my intercooler hoses. I'm not sure yet if it will help keeping some of the engine heat away from the hoses but for less than $1.50 is worth trying, I think.

olddragger

iTrader: (3)

Thats a cool idea--pun intented Everything helps. I am working on some ideas. By the way I will be sending the intercooler to ya--i found that if you tilt it more than approx 15 degrees then hardly any airflow comes through(using just a reg house fan)--i can provide more details.
Here is something interesting--------------------------------------------------
This morning ambient at 74F. I hooked a temp probe up to the air filter(I do have the rb air scoop on). I started out to work--regular 45 mph stop light traffic and very little trafdfic this a.m. The temp on the air filter was 77-78F. Air scoop doing it's job right? Engine temps were normal etc. OK i get closer to the hospital i work at and it gets to be more city type driving --right? Had to stop at a couple of red lights---temps slowly creep up to the low 90's but cools SLOWLY when i start moving. Thats ok i am thinking.( By the way iat's in low 90'sF). Ok I get to the parking deck and have to go up in 2nd gear --4 decks--- speed limit 10mph--when i park the car I look at the air temp of the intake filter and it has climbed to 137 degrees F!!!! Holy Mother of God----Bingo! Now THERES a problem as it would take a long time to cool that off again. The iat had climded to 109F.
So at low speed ---BIG HEAT SOAK PROMBLEM OF THE INCOMING AIR.
Guess what my next project is going to be?
We may need to chase more than one squirrel here
Now people without the rb air duct---just imangine what is happening?
olddragger

avanti_racing08

ok, im new to the RX8 world. but always loved them, soi finally got one. it is only being used to do rallys around the country. In the futer i will be adding alot more power. Where would i be able to pick up this SC and where is there a shop that could install? I live in CT but will travel to have it installed right.

Mazurfer

Must Read!

This particular SC talked about in this thread is by www.pettitracing.com and they are located very near Palm Beach, Florida.
However, there are probably a few people that would come and install it in Conn. for you.

avanti_racing08

theres 86 pages thats alot lol

Mazurfer

Valid point. I guess I've been lucky enough to keep somewhat up on it since day one.

morkusyambo

Not much to keep up on. A few pages of solid info and the rest is normal internet forum "stuff".

Bastage

iTrader: (1)

Your warranty should be close to halfway over by now... so have you decided on a date to get FI'ed yet?

How's the foot?