Beginner mods
11-02-21, 10:22 AM
#1
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Beginner mods
I have an 88 s4 rx7 with a rebuilt s5 engine (street ported), I've currently replaced the radiator with an aluminum one with an electric fan as well as upgraded all the coolant hoses. Besides a full suspension and cooling, the only modification for power has been a full racing beat exhaust I put on last spring. I'm planning on doing a proper CAI with a heat shielded box next spring, but does anyone have any suggestions for a little more power? I don't want to boost it but I have played with the idea of bridge porting it at some point. Any suggestions would be much appreciated! Thank you!
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mr_vaughn (11-04-21)
11-02-21, 12:19 PM
#3
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there are a bunch of little things you can/should do, they kind of fall under the 'tuning' umbrella, although most of it is just making sure that all the stuff works.
the FC has a lot of adjustments, and when you have them all in the right place it makes a big difference. i treat the thing like a stock class race car,
Fuel: you want to have a fresh fuel filter, but also the in tank pump sock. its NLA from Mazda, but the ND one is the same 952-0043
The S4 runs a pretty optimal fuel mixture (on a stock car its in the 12's), if you did go dyno it, something to fine tune the fuel would be ok.
Ignition: stock spark plugs are ok, but should be changed more often. stock is 30k miles, and 15k is probably the maximum for a performance type thing
you can test or replace the wires, the resistance on a new NGK wire is about 8k ohms, more resistance = less ignition power, so this is important.
also you want to either route the trailing wires away from each other and the leading, or cross them all at 90 degrees. there is a thing called 'inductive cross fire' and it breaks engines, so we want to avoid it
you should try adding a degree or two of timing, the S4 usually likes it. if you hear any weird noises or it doesn't run right put it back.
Intake: you want to make sure all the valves and stuff are working, and rotate freely, you can move em by hand. you also want to make sure the throttle opens all the way.
apparently just a cone filter and a little flap to keep the radiator air away is good enough. oh also the hose from the AFM to the engine is huge on the outside, but small on the inside, so there are gains to be had there.
also experimenting with the opening time of the 6 ports (if you're still using it) makes a big difference.
Exhaust: this is probably not fun, but the exhaust ports are 48mm and the header is 44mm, so you can port match it.
Other: clean the damn windows, its a placebo, but it makes the car run better. i also spend a lot of time getting the seat in the right place, and the pedals have some adjustment too.
set the tire pressures, for a street car, 32psi cold is good. obviously the alignment makes a big difference (i've posted numbers before). also there is some weight to be pulled out of the car, AL hood, you can ditch the spare, if you combine that with a catback its like 60-80lbs, which is good, and you've kept the full interior and AC and stuff if you like. modern stereo would be lighter too.
the FC has a lot of adjustments, and when you have them all in the right place it makes a big difference. i treat the thing like a stock class race car,
Fuel: you want to have a fresh fuel filter, but also the in tank pump sock. its NLA from Mazda, but the ND one is the same 952-0043
The S4 runs a pretty optimal fuel mixture (on a stock car its in the 12's), if you did go dyno it, something to fine tune the fuel would be ok.
Ignition: stock spark plugs are ok, but should be changed more often. stock is 30k miles, and 15k is probably the maximum for a performance type thing
you can test or replace the wires, the resistance on a new NGK wire is about 8k ohms, more resistance = less ignition power, so this is important.
also you want to either route the trailing wires away from each other and the leading, or cross them all at 90 degrees. there is a thing called 'inductive cross fire' and it breaks engines, so we want to avoid it
you should try adding a degree or two of timing, the S4 usually likes it. if you hear any weird noises or it doesn't run right put it back.
Intake: you want to make sure all the valves and stuff are working, and rotate freely, you can move em by hand. you also want to make sure the throttle opens all the way.
apparently just a cone filter and a little flap to keep the radiator air away is good enough. oh also the hose from the AFM to the engine is huge on the outside, but small on the inside, so there are gains to be had there.
also experimenting with the opening time of the 6 ports (if you're still using it) makes a big difference.
Exhaust: this is probably not fun, but the exhaust ports are 48mm and the header is 44mm, so you can port match it.
Other: clean the damn windows, its a placebo, but it makes the car run better. i also spend a lot of time getting the seat in the right place, and the pedals have some adjustment too.
set the tire pressures, for a street car, 32psi cold is good. obviously the alignment makes a big difference (i've posted numbers before). also there is some weight to be pulled out of the car, AL hood, you can ditch the spare, if you combine that with a catback its like 60-80lbs, which is good, and you've kept the full interior and AC and stuff if you like. modern stereo would be lighter too.
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mho2023 (07-18-23)
11-02-21, 12:36 PM
#4
Rotary Freak
In addition to all the other good advice in this thread, I've been thinking about intakes lately.
You likely aren't going to meet or exceed the stock intake unless you put some serious design into it. You mentioned making an airbox, so that's definitely a start. The stock airbox already does this though, so you need to improve on that if you want any gains. The only place that I see significant room for improvement with the stock airbox is that the snorkel runs along the top of the rad, and therefore gets hot sometimes. I don't know if this imparts enough heat into the intake charge to make a difference, but in theory we could improve upon this design by avoiding that path.
I've been thinking that the best way to do it would be to get one of those MAF adapters that lets you run a standard cone filter. Instead of using a filter right on the adapter though, get silicon joiners and aluminum pipe and source it from in front of the rad. One way would be to cut as if installing a front mount intercooler and go that way. The other way (preferable IMO) is to run the pipe down under the car in the same way that the air pump silencer tube goes. You would lose some ground clearance depending on routing though. If you have no air pump / delete the silencer, you could fit an air filter in that location and it would be inhaling from the wheel-well area. Otherwise make turn and cut the under-tray and you should be able to put the filter in front before the oil cooler.
Would the gains be noticeable? Probably not. Just food for thought.
You likely aren't going to meet or exceed the stock intake unless you put some serious design into it. You mentioned making an airbox, so that's definitely a start. The stock airbox already does this though, so you need to improve on that if you want any gains. The only place that I see significant room for improvement with the stock airbox is that the snorkel runs along the top of the rad, and therefore gets hot sometimes. I don't know if this imparts enough heat into the intake charge to make a difference, but in theory we could improve upon this design by avoiding that path.
I've been thinking that the best way to do it would be to get one of those MAF adapters that lets you run a standard cone filter. Instead of using a filter right on the adapter though, get silicon joiners and aluminum pipe and source it from in front of the rad. One way would be to cut as if installing a front mount intercooler and go that way. The other way (preferable IMO) is to run the pipe down under the car in the same way that the air pump silencer tube goes. You would lose some ground clearance depending on routing though. If you have no air pump / delete the silencer, you could fit an air filter in that location and it would be inhaling from the wheel-well area. Otherwise make turn and cut the under-tray and you should be able to put the filter in front before the oil cooler.
Would the gains be noticeable? Probably not. Just food for thought.
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