CrossfireForum - The Chrysler Crossfire and SRT6 Resource

CrossfireForum - The Chrysler Crossfire and SRT6 Resource (https://www.crossfireforum.org/forum/)

- Engine, Exhaust, Transmission and Differential (https://www.crossfireforum.org/forum/engine-exhaust-transmission-differential/)

- - 78mm TB (https://www.crossfireforum.org/forum/engine-exhaust-transmission-differential/78872-78mm-tb.html)

https://cimg3.ibsrv.net/gimg/www.cro...bdc571203.jpeg

MAXBORE unit 75 to 78mm.
I have two 05 coupes a SRT and manual NA, both with the single CAI. Last year I got a 75 mm TB to upgrade the NA but decided to send it to MAXBORE and have it modified. He fluted and bored it out to 78mm, it looks nice. The plan was put it on the SRT and use the stock 75 on the NA. I put it on the SRT and the car ran terrible, I had read that the computer needs time to adjust but after driving around the parking lot it still would barely run. I pulled it off and went back to the stock 75 mm TB. The car still ran terribly until the codes were reset.
So I have this 78mm TB and I am thinking that the stock engine can not pull enough air for it to work, but maybe a modified engine with the smaller pulley that moves more air might work. So would someone with a moded SRT like to try it and see if it produces more power and works with the higher power engines. I plan on putting on a smaller SC pulley in the future but right now just doing suspension work, so would be willing to send this for someone to try and if it works then swap for a stock 75 to put on the NA. If it still not working right maybe it is the electrical pat of the TB that is not working.

Quote:

Originally Posted by DHS (Post 911444)

When you change your throttle body to a larger one you should force the computer to relearn by doing this:

Turn the Key to the "on" position (the position right before you start your engine)

Press and hold your gas pedal down for 5-10 seconds

Turn Key to "off" position (don't remove the key) and then release the gas pedal.
than wait at least 2, if not 3 minutes, for the system to reset.

If done correctly you will hear some clicks coming form the throttle body as it relearns and adjusts. And of course if you are at the maximum threshhold (due to your other mods) of your current ecu calibration then a re-tune is required. I do this upgrade on my slk32s all the time along with turned down (74mm to 69mm) sc pulley and high flow filters, and never had to retune, computer is able to adjust for the difference, although we do that just to accomodate better performance and more hp. and we always do the throttle body reset/relearn procedure, so the ecu knows its gonna get different readings.

I have a Maxbore bored throttle body on my car. No problems with it at all ..... however, I've not seen any benefits from the enlargement. Perhaps with a modified inlet that would change. But then I'd also get an 83mm throttle body. I'm guessing yours has an issue not related to the increased bore.

Les

Well I did not try that, I sent it to another owner to try, he has a 62mm pulley and the higher pressure fuel pump. It ran poorly on his car, I will ask him about that reset, I do not think I did that.

the issue is that when you enlarge the port, the plate needs to be enlarged to keep the gaps the same at idle and normal driving. when this step is skipped you end up with too large of a gap between the plate and bore and the car runs like crap. i have seen several customers get burned by this so far. once they get it ported, there is no going back so they end up needing to buy a unmodified throttle body to get the car running correctly again. most companies that port throttle bodies do not bother to make larger throttle plates to match up.

I think far too many people get it wrong when trying to increase air flow without having a good understanding of airflow principles and an airflow bench at their disposal. Larger is not always better!! A better approach is to cleanup the airflow by polishing, making any bends less angular, making them equal, etc. If you enlarge everything, you increase the potential max airflow but you may have decreased the actual flow due to decreased velocity. You also have to be concerned with your exhaust. You can't get more in if you can't get it out. These engines were designed and built by experts (AMG) so don't expect a huge gain without modifications of the entire system; more air means more fuel, a larger capacity pump, maybe larger injectors, etc. Read what others have done, take it in small steps. If one mod, on it's own can net +20 hp and another mod can net + 25 hp, that does not mean together they will net + 45 hp. It might be more like 35 combined.