I have the JDM ITR engine with 11.3CR, TODA specB, Spoon header, test pipe, and Kakimoto R catback exhaust. I am currently using stock fuel system with Yoshio programmed OBD2 P30 ECU and VAFC. Right now, I have to add like 10-15% of fuel with the VAFC to make it run not fully lean according to the Greddy A/F meter.
So I want to upgrade to a larger injector. Should I get the RC 310cc or the 370cc one? I heard that both will able to use with the ECU(stock 96 DelSol one chipped by Yoshio) I have now, so I am leaning toward the 370cc one because I can run lower fuel pressure and duty cycle.
Any suggestion or comments?

 

I would give the 370cc a try. Like I told you my car react like stock with the 310cc. The 370cc should´nt be a problem. I would recommend a fuel press. gauge and a AEM fpr too. Then go on a wide band O2 dyno and sqeeze some hp out.

How much whp do you have now? Maybe a fuel pump upgrade would be nice?!

I have now max. 65psi fuel press with my JRSC at 5.5psi boost. CR is 11.1:1. This is tuned with VAFC and Cartech FMU at 195whp. My car has stock only 151whp, I live in 750 meter elevation and it was a hot dyno day too. We have not the SAE hp, we use the DIN numbers. I think in the USA I can hit about 205whp. The 310cc and VAFC goes out and I´ll upgrade to 440cc with an Haltech E6K ECU

BTW: The JDM type-R engine has 11.1:1 CR. We in Europe have them and it is writen in the R´s manual.


[Modified by austrian ITR, 1:59 AM 11/27/2001]

 

Thanks for the advice, so I guess 370cc would be better since I am upgrading it anyways. I really don't want to change the injector and still have to run high fuel pressure and high duty cycle.

I have the Spoon headgasket, that where the 11.3CR come from. I don't have a chance to dyno my car yet too.

I will get the B&M fuel pressure gauge and probably their FPR too. Unless someone can convince me the B&M one suck big time and the AEM or SARD one really worth the extra $100!!

 

The B&M is limited in its adjustment range. 60X is as high as it will go. Not sure how low it will go, but chances are with 370s and your setup, you will not require as much pressure.
Sounds like if you only need 10-15% more fuel with the stock injectors, you will be better off with 310s. RC rates their 310 at 43.5 PSI, so at stock ITR pressure, they are more in the 330 range...


Jason

 

Is there any disadvantage with going larger injectors than I actually need? Assume both cost the same.

I always think lower fuel pressure and duty cycle is better, am I right?

So let say if I get the 310cc, I will need to run stock pressure and 80% duty cycle. With 370cc I can run 10 less PSI and 70% duty cycle. I would be better off with the 370cc?

 

That is a good question! I don´t know exactly, but I would´nt go under the stock fuel press.

 

How do you like that Greddy AF meter? I'm thinking I'm gonna need to upgrade my injectors too,

 

First, since you have an OBD1 chip I suggest that you send ask Yoshio to re-program the ECU for whatever size injector you eventually get...I assume he did your current program all based on stock injector sizing.

Secondly, if you go with a 370 cc/min you definitely need to send the chip back since the calibrations for the fuel map would be thrown off with that big of an injector. The Hondata.com Tech FAQ section tells you why 310 cc/min injectors are the largest injectors acceptable for any OEM chip fuel map. The VAFC just won't cut it when you start getting into sizing above 310 cc/min.

I thought the VAFC freaks out if you exceed 11% increase in fuel setting since the amplified MAP signal would make the ECU think you are running boost and turn you over into limp mode? I guess with the P28 chip, the MAP maximum threshold is higher.

I'd definitely call (if he ever answers his phone) or better yet email Yoshio and ask for his suggestions.

cheers

 

I would go with 270. I have 310's on my car now and i'm running a bit rich. i have 12.4 compression via toda pistons and spec b's.

Yes, running an injector that is too large for your setup is really bad. You would have to turn down the fuel pressure and this would effect spray pattern. I would try 310's but i think that they will be a bit too much for your system.

 

I like my 440's...

 

I like it a lot when it is working properly. But the problem with mine is it always give the short wire signal.

 

I have the OBD2 ECU, so it cost a lot of $$$ to reprogram it again, so I don't want to do it unless I absolutely have to. Even when it is absolutely have to, I will go with Hondata.

Anyway, I just called Yoshio to ask for his help. He said I should just get the injectors that is just big enough for my application. Because he said it is better to run higher fuel pressure than lower because of something that I can't really understand. He told me the 290cc Prelude one should be good enough and the OEM quality is usually better than the aftermarket rebuild one. So right now, I will get either Prelude 290cc or the RC 310cc.

 

Like i said in my earlier post. It is for fuel spray optimization. imagine a shower head, with low pressure vs high pressure. The spray pattern in the high pressure water is more even and consistent.

 

Ben...After extensive talks with RC Engineering we decided to use 440cc/min injectors on my car as they have a better atomization pattern than the 310's, or the 370's as they have 3 discharge ports as opposed to 1 discharge port for the 310's and the 370's...my fuel pressure is around 50 psi at full throttle.
Austin

Hopefully I can take a look at your car again when I'm down for a meet.