View Full Version : Pettit S/C hints and tweaks


olddragger
06-17-2008, 11:53 AM
I thought I would start a thread just for the "little" things that has been done to taylor the system to the owners taste and use. We all know the system works well as sold--but hey we know we cant leave things alone---right? here are some of mine
1- buy a water meth system --have one nozzle after the blower and one before the blower if you like. water meth system and 93 oct gas is equal to lower iats on demand and 116 oct gas!
2- buy a water meth system---said AGAIN.
3- upgraded the bypass valve. can get them from e bay (check with juan) or companies. i am running the turboxs --do not run a spring in the valve per Cam.
4- stock a/w coolers--run in parallell only , move the return line to the reservor away from the alternator--it gets real hot., mount the coolers as far away from the a/c condensor as you can and make them as vertical as you can.
5- seal the front air supply to the i/c, radiator---add that second air blocking plate, seal the sides and top--do run a small 3 " flex air hose from the back of the grill to the air inlet of the engine bay
6- the rb air scoop causes a recirculation swirl at the top part of the radiator-- i took mine off.
7- make sure the s/c belt is not too tight
8- it is good to get an a/f gauge and a boost gauge(can tell if you belt is slipping)
9- get the efi dude or some way to data collect for better tuning, checking your ltft etc. for instance I found my oem tach was off by 500 rpm once it got at 7K.
10-- get REAL gauges--you dont need an oil pressure gauge. get an intake air temp gauge --it can be mounted in the old pettit air temp monitoring site. that way if the pump ever loses prime etc you can see you intake temps really rising and not go into boost until it is fixed. could save your ass.
11 -- heat shield the bottom part of the old air box we use and also heat shield the top part of the header and the side part of the box between the water reservor and the overflow tank.
12- run the cold rx7 plugs without a washer on the lead side and with 2 additional washers on the trailing side. The stock plugs are recessed too much and without a washer (or that little bitty bar) the lead plug can get futher into the combustion chamber. Clean the lead plug hole really well whenever you take that plug out--it is a haven for carbon buidup and hince detonation sites. the additional washers on the trailing plug is just to insure the plug will not bottom out and therefore not seal well.
13- i dont run underdrive pulleys--my water pump needs the rpms. i do not go over 7.5 or 8k any longer.
14- use a big type of lawn mower gas filter for an oil catch can if you are tracking--dont need it for the street.
15 you dont have too but relocating the ol filter to the w/w firewall is nice(and increases oil capacity a little) you can use the mounting bracket that Mazsport sells and a e-bay relocation kit--use real aircraft type lines or the flex kind--just remember to isulate them from the intake
16--my engine sure moves much more now under full throttle--i am looking for a engine damper at present.
17-- support the end of your air filter. that straight tube can bounce a little and that has the potential to make the maf readings wrong
18 - i do a decarbon tx every 3 months, i do run pre mix (keep a good fuel pump in the car--i replace mine every 2 yrs regardless) i run 1 oz per gallon on the track and 1/4 oz per gallon on the street
19- an ignition upgrade is real good---do a spark test on the oem one and you will see what i mean.
20 -disable the vdi
enough for now
How about you other people--what have yall done/recommend?
olddragger

Dogpound48
07-06-2008, 09:29 PM
One thing I would like to add is to make sure that you have enough clearance with the strut brace. I was chasing engine noise for weeks to only find that the S/C was bumping the brace under certain load conditions. It even sounded like it was detonating.

california style
07-08-2008, 04:13 AM
One thing I would like to add is to make sure that you have enough clearance with the strut brace. I was chasing engine noise for weeks to only find that the S/C was bumping the brace under certain load conditions. It even sounded like it was detonating.

a couple of small washers under the strut brace sort this out nicely...

MazdaManiac
07-08-2008, 04:46 AM
9- get the efi dude or some way to data collect for better tuning, checking your ltft etc. for instance I found my oem tach was off by 500 rpm once it got at 7K.

All RX-8 tachs read +500 RPM across the board. The speedo is also off by 3 MPH. This is a long-known issue.

12- run the cold rx7 plugs without a washer on the lead side and with 2 additional washers on the trailing side. The stock plugs are recessed too much and without a washer (or that little bitty bar) the lead plug can get futher into the combustion chamber. Clean the lead plug hole really well whenever you take that plug out--it is a haven for carbon buidup and hince detonation sites. the additional washers on the trailing plug is just to insure the plug will not bottom out and therefore not seal well.

The OE plugs have a perfect reach with no recess.
The reason you don't run the RX-7 trailing without a washer is that it will warp the housing, not just fail to seal.

13- i dont run underdrive pulleys--my water pump needs the rpms. i do not go over 7.5 or 8k any longer.

Why not? You should be making power up there, especially with the way the supercharger makes power, right?

16--my engine sure moves much more now under full throttle--i am looking for a engine damper at present.

It shouldn't.
The OE mounts have a limited range of motion. You might simply have a blown mount.

17-- support the end of your air filter. that straight tube can bounce a little and that has the potential to make the maf readings wrong

The kit still doesn't have a filter brace???

18 - i do a decarbon tx every 3 months, i do run pre mix (keep a good fuel pump in the car--i replace mine every 2 yrs regardless) i run 1 oz per gallon on the track and 1/4 oz per gallon on the street

With all that water/meth, using Seafoam or the equivalent more than once a year is overkill. Especially if you are using a good pre-mix.
The Sohn adapter is even better.

19- an ignition upgrade is real good---do a spark test on the oem one and you will see what i mean.

Unless your OE coils are actually failing, a "spark test" will reveal nothing.
An ignition upgrade is needed for serious power, though.

20 -disable the vdi

I'm still waiting to hear the explanation for that one.

Rote8
08-14-2008, 01:53 PM
Replacement Inter-cooler reservoir cap (http://tewarehouse.com/7-07565;jsessionid=0a0107431f43de4e5de29fbb4377b4ab9 debaf625845.e3eTaxiPc3mTe34Pa38Ta38Lc3z0)

I cranked mine down too hard.....
I found my lawn mower's gas cap fit, sooo......

morkusyambo
08-29-2008, 12:44 PM
I am currently using the RB air scoop. OD, would you explain what you mean by recirculation swirl?

olddragger
08-29-2008, 06:18 PM
the top 1/3 of the radiator area will develop a swirl type current at speed. sort of like a swirl current associated with a waterfall. what this does is to diminish the air flow through the radiator as the air is swirling. SOme old threads from some austral guys spoke of this also and during some of there lonngg high speed runs over 120mph their cars will actually run hotter and be down on power. the rb airscoop shapes the area so as to predispose to swirling.
olddrgger

swoope
08-29-2008, 09:17 PM
the top 1/3 of the radiator area will develop a swirl type current at speed. sort of like a swirl current associated with a waterfall. what this does is to diminish the air flow through the radiator as the air is swirling. SOme old threads from some austral guys spoke of this also and during some of there lonngg high speed runs over 120mph their cars will actually run hotter and be down on power. the rb airscoop shapes the area so as to predispose to swirling.
olddrgger

think rotor currents..

beers :beer:

Rotr8
08-29-2008, 09:58 PM
can this be solved, say if, thier were a sleeve or tube that ran from the out end of the RB duct to the filter and encased it??? I f I was planning on builing one like that since I too own te RB duct, it would give a somewhat sealed CAI effect...

Wind Dance
08-30-2008, 01:05 AM
Maybe this ram air would impose less swirling..
Odula Type M... not the RS
http://japanparts.com/images/ImageFromDB.php?base=1&no=11778

olddragger
08-30-2008, 12:58 PM
sure you can add something to channel the air better and the ones above would probably be better. the rb one goes almost all the way across. that M one is still obsene:)
olddragger