Non-turbo 428rwhp FD build up and history by GtoRx7

By diyauto
( 5 )

4 minute(s) of a 136 minute read

11-25-2011

Chapter 1- recovery of lost horsepower


Alright I figured out how to save the dyno charts on this computer. So, as some of you may recall, I installed a new 3.5" exhaust this spring, and it lost some hp. Alot of hp. I was concerned that it was the diameter that killed it. BUT turns out the exhaust gaskets I used on the header (which were aftermarket, and softer) blew out the first time the engine fired up. The header leak was so bad it dropped 32 horsepower. This shows how important the proper velocity is in a n/a engine like this! 


So I removed the header, put back on the stock turbo style gaskets which fixed all the leaks. Result? 432  This was without the race plugs, which add 2hp. So that is 434, right back to where I started. YES!! now I could continue to test new setups. 




Chapter 2- finally real intake testing 


So this marks the point where I started to get more serious in my attempt at very high n/a horsepower. Up till now, I was using stock based intake systems and quickly made p-port manifolds. No ITB's, or even real air horns. That had to change.


Even though the new prototype teflon slide throttle setup had too much friction during running, I just did a hillbilly modification and added a **** ton of return springs. The throttle felt like a clutch pedal but I didnt care. Just needed it for dyno testing  The actual slide throttles are being machined and are fully ball bearing supported.


Here is the pic of the new intake, which is full ITB, slide throttle, velocity stacks and external bell mouth injection. Bosch 550cc injectors for more atomization (same as ID 550cc)






This new intake was fully adjustable in length. So I started at a very long length, and worked my way down 2" at a time. The longest length still showed HUGE promise. The increase in torque was exciting, over 30ft-lbs at 6800, and 8ft-lbs higher than previous peak. 




Each time the intake was adjusted, of course the torque shifted upwards. As the torque grew, the injectors maxed out. I turned up the fuel pressure, did all types of things. Couldnt get the afr over 8500 to be in range. High 14's to 10k. This hurt top end hp, would have been 438-440rwhp if I had more fuel. Peak torque however was now at 267 which is a 17ft-lb gain over the previous best!



Power under the curve was more than substantial. The was the end of dyno day #1. No way could I stop just there.



Chapter 3- quest for more. 


The days to come, I started to think a bit harder. Reviewing and crunching my old calculations vs. the new data. Then, Carlos Lopez happened to give me a call. During our usual conversation about all things rotary, he brought up something. That man will forget more than most will ever know. Totally by coincidence he made me realize a error I had been making for quite some time.


So I busted my *** and did all the revisions I had pondered about. And went back to the dyno where the really impressive stuff happened. 


Chapter 4- where all the fun began 


I will post all that very soon 



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