View Full Version : Stock boost or can I go higher?
04-03-2003, 12:19 PM
My 85 5mge has 20K on it, is getting a new MHG and is bored .030 over with non-forged pistons and stock rods. Would I be able to go any higher than stock CT26 boost (provided I put in an RRFPR)?
Also is it worth the money to get the head ported and the throttle body bored?
04-03-2003, 11:59 PM
You have to have a RFPR for the CT26. To go any higher add some 295cc injectors.
Porting will help any car but really isn't necessary on a force fed motor.
04-04-2003, 11:33 AM
I have 7mgte injectors on the way. So with the larger injectors, an rrfpr, MHG what should I limit my boost to? The first time I drive it when it gets back together it is going straight to the dyno.
04-04-2003, 12:43 PM
CRF-Rider, I don't think 440's would work using 5m fuel/elec system. Only for 7mgte's. Sorry to break the news...maybe I'm wrong that 440's could be made to work with stand alone electronics.
BTW, do you own a Honda CRF450? If so, what type of riding do you do?
04-04-2003, 01:53 PM
Hmm. Well, I only paid $40 for the injectors so no big deal. I am sure I can get that out of them. Can anyone tell me if for sure if the GTE injectors will work with the stock ECU or should I just use my stock injectors?
I do have an 03 CRF. I ride MX at all the local tracks. I was going to get my suspention done this weekend but I have decided to turbo the car instead. Now I may have to sell my Telescope to get all the toys I want for the supra.
04-04-2003, 03:05 PM
the 440's are way to big for stock fuel system, i thing 7m-ge injectors have been used with ok results (315 i belive) but i think even those are a bit to big for the stock fuel system, i think 295's are the way to go
hth, good luck
04-04-2003, 08:51 PM
the 7M-GE injectors will work. The flow rate depends on the year of Mk III they cam out of. If they are Pre-89, then they flow at 295 CC/min and are low impedance. If they are 89 or after, they are 315 cc/min High impedance injectors. I personally recomment the 295's. Install is much easier (just swap the clips and your good... no resistor packs to bypass).
The 440's will NOT work with the stock 5M electronics. You will be so overfuled that you won;t even start. The 295's need some kinda of piggy back or stand alone management as well, tho some people have gotten them to work without it by leaning the AFM almost 1 complete turn of the wheel. I personally wouldn't reccommend that route, but I tend to be conservative when I build fuel systems...thats just me... :)
An RRFPR will supprt you with enough fuel to run ~6 to 8 PSI. You have to be careful with RRFPR's tho, as the increased fuel pressure will tend to wear your injectors and FPR faster... and 100 PSI of fuel just can't do good things to the parts...
04-06-2003, 10:30 PM
To me RRPFR is a cheap way to make a fuel system set-up.... I suggest a 1:1 FPR like AEM or so and a piggy back like HKS S-AFR with like a 295 cc injectors to got past 8 psi on a stock CT-26 turbo set-up to a 5M/6M turbo set-up.... it will supply you enough fuel with out the worry of to much fuel and the problem with idle.... there is some injectors that fail already for the sense that the pressure in the fuel system is too much to be handled by the injectors itself with using the RRPFR... just my 0.02 cent opinion
04-07-2003, 12:28 PM
What is involed in hooking up the S-AFC? Where do you have yours mounted? Where is the best place to get one?
04-07-2003, 10:09 PM
This is a sale on the HKS Super AFR for $290.00 on http://www.Titatmotorsports.com and hoooking it up... is fairly easy... just follow the wiring instructions to hooking it up on your computer and have a handy wiring diagram of your car and tuning it would require a dyno and a wide band O2 sensor to get the best tuning result
04-07-2003, 10:22 PM
$275. I think I will do without if I can.
The local engine builders are telling me it is a bad idea to boost the 5m without forged pistons. I may scrap this project and do a 7mgte conversion. Still doing research though.
04-08-2003, 04:18 AM
I'm pretty sure the 7M-GTE doesn't have forged pistons either....could be wrong about that though.... :?
04-09-2003, 02:22 AM
There is a lot of MK2 owners that turboed their 5M motor but has no problem with it.... going forged pistons is a good insurance for the motor you are building...
If you are gonna be going all out.... might as well get forged pistons
I have a friend who owns a dodge omni w/ 2.2L Turbo engine and runs mid 11sec and is still using cast factory pistons but have run to about 3 rebuilds of it already due to the fact it is not as strong as a forged pistons... he still has cast pistons but he told me that when this pistons go again... eventually he will buy a forged set so that we don't have to pull his engine again for the 5th time
04-11-2003, 03:32 PM
I have forged pistons - just dont know anything about'em ... I bought the block knowing it had lowered compression and forged pistons.
I've blown 2 FPR's because of a shitty adjustable RRFPR which made a wayyy to high fuel pressure in between the FPR and RRFPR ... I opened up the first FPR that I "blew up" - the gasket where wasted. With the result that the fuel return went straight into the vacuum hose instead of the fuel hose, and into the intake plenum, causing a flodding of all 6 cylinders in no time !!
Now I've turned down the pressure as much as possible - and running only 5 psi, I cant hear any knocking so I think I'll be fine for now. I have no o2 sensor, only AFM.
My future plan is to add 2x440cc injectors in my intake - just before the throttle body, and with a Map Fueler system attached, which will engage in several steps upon boost etc. This way, the fuel will get into all 6 cylinders, and I wont loose a piston in case one of the injectors happen to fail. You'll never know. I've heard of several people using this setup, and it works. Its not the best - but it works. The best is of course the right size injectors and some piggy backs.
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