Getting an NA FC into the 14s in the 1/4 mile
11-16-09, 02:44 PM
#1
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Getting an NA FC into the 14s in the 1/4 mile
I have been an American muscle car type guy and am new to rotary stuff. Reading through people's turbo build threads makes my head spin, with all the different combo's people come up with. Would it be possible to put my good running naturally aspirated FC into even the high 14s in the 1/4 mile, with some work but without spending so much that it would be pointless on the NA setup? I got this car just to have something small and nimble to autocross with. I don't need it to run a 12 second 1/4 mile. Just curious what the potential of the NA engine is. Sorry for the newb-ish question
Steve
Steve
11-16-09, 04:49 PM
#2
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Without opening up the motor you're really limited to maybe 180whp if you're lucky and do everything you can to make power. With opening it up and keeping it streetable, maybe 200whp is a realistic, slightly high goal. I'd think you'd be better off leaving the engine more or less stock and concentrate your efforts on lightness and traction.
11-17-09, 05:49 AM
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exactly, GTORX7 did 230rwhp with street port and shortened cosmo intake. Sad thing is that some people struggle to make 200rwhp even with itbs and more agressive porting...
11-17-09, 06:33 AM
#5
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I was able to do 14 flat (well, 14.04) in a 2500lb car with an engine that does 170, maaybe 175whp.
That's with short times in the 2.1 range.
I know that there is more power to be had in a different intake manifold, but I really like the part throttle and midrange RPM drivability of the stock setup. That is far more important to me than a dyno number or an ET. (Although I was really hunting for a 13.xx on the 680 injectors!)
The only time I ever get to use peak power is right before I shift, so what good is it? I'm much better off trying to make more torque in the 5000rpm range where the engine falls to after a shift. You don't get faster by making the fast parts faster, you get faster by making the slow parts faster. (Do you care about your 60' times or your 1000'-1320' times?)
With that in mind, I am thinking of adapting a 6-port's intake manifold to my Turbo II block, with port matching this time. The longer runners should be beneficial. Barring that, I might have to suck up my pride and go forced induction. Or bridge port. Or V6.
That's with short times in the 2.1 range.
I know that there is more power to be had in a different intake manifold, but I really like the part throttle and midrange RPM drivability of the stock setup. That is far more important to me than a dyno number or an ET. (Although I was really hunting for a 13.xx on the 680 injectors!)
The only time I ever get to use peak power is right before I shift, so what good is it? I'm much better off trying to make more torque in the 5000rpm range where the engine falls to after a shift. You don't get faster by making the fast parts faster, you get faster by making the slow parts faster. (Do you care about your 60' times or your 1000'-1320' times?)
With that in mind, I am thinking of adapting a 6-port's intake manifold to my Turbo II block, with port matching this time. The longer runners should be beneficial. Barring that, I might have to suck up my pride and go forced induction. Or bridge port. Or V6.
11-17-09, 07:49 AM
#6
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Thanks guys. See peejay, what you have would be more than fast enough for me, I guess I need to pick your brain. I like your thinking re: making the car stronger in the rev range where it will be beneficial on the street, rather than just making a more impressive dyno slip at 9 million rpms. I don't mind opening the engine up if I have a plan laid out with the help of people who know what they are doing w/ the rotary engine. Even though I'm not going to be drag racing the RX7, I don't want it to be the slowest of my 5 car fleet either. My 300+ hp V8 cars aside, right now even my 200 hp daily driver Taurus is faster than the 7 and I want to fix that.
11-17-09, 11:48 AM
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i know a couple people who were running high 15's in FC's with intake/exhaust and some driving skills...
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11-17-09, 06:57 PM
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11-18-09, 02:11 AM
#10
exactly, GTORX7 did 230rwhp with street port and shortened cosmo intake. Sad thing is that some people struggle to make 200rwhp even with itbs and more agressive porting...
Exactly as Black91n/a said, that 230RWHP is on a 4 port motor- the 6 port motors really do struggle to make it to 200RWHP.
Exactly as Black91n/a said, that 230RWHP is on a 4 port motor- the 6 port motors really do struggle to make it to 200RWHP.
11-18-09, 07:19 PM
#11
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(I hate laptops... keep tapping the mousepad by mistake)
I also have a four port engine. N/A internals in a Turbo II shell.
There are ITS guys making more power than me, some of them on stock ECUs with external tweaking.
Which all makes me wonder
- What are they doing
- What am I doing wrong
- How can I get from here to there
Paul Yaw made a similar setup to mine and yielded something like 210 at the wheels. (http://www.yawpower.com/sep2004.html) I think his exhaust ports are better (no, really?) and his pre-throttlebody intake is loads better than my filter stuck on the throttlebody.
More importantly, my engine has tons of blowby, probably because I stuck 160k old side seals onto a different set of housings and just let 'er rip
(Apex seals were replaced with something I could trust to 10k+ mis-shifts) It quit oil smoking but it still has enough blowby that I need to change the oil after a rallycross because it gets loaded with a ton of fuel. New side seals and cleaned up side housings will be on order this winter when I pull the engine apart to fix the coolant problem. And the exhaust port problem
Anything you can do with a stock type intake manifold will not rev very high, so it doesn't make sense to try to stack the powerband to the right side of the tach. For all its fun my engine only makes noise over 8500, and even then it sounds very "flat" up there.
The powerband feels a lot like my 6 port did except there's just more of it everywhere. Good power until about 5500 and then it tacks on a bunch more and then starts falling off almost immediately. My streetported 12A also felt the same way, actually, with power/torque about the same as the 6 port 13B.
I guess what I am getting at is, if you are "only" looking for mid-high 14s and know how to drive a car, you should be able to do it with a 6 port with no problem. Focus on getting a good exhaust system on it, it's critical. (Look up GTORX7's thread on getting to 230whp, I think the exhaust and intake were worth 40 of that with the same engine)
I don't think there are ANY gains to be had in the throttle body, it is not the restriction in the system.
I also have a four port engine. N/A internals in a Turbo II shell.
There are ITS guys making more power than me, some of them on stock ECUs with external tweaking.
Which all makes me wonder
- What are they doing
- What am I doing wrong
- How can I get from here to there
Paul Yaw made a similar setup to mine and yielded something like 210 at the wheels. (http://www.yawpower.com/sep2004.html) I think his exhaust ports are better (no, really?) and his pre-throttlebody intake is loads better than my filter stuck on the throttlebody.
More importantly, my engine has tons of blowby, probably because I stuck 160k old side seals onto a different set of housings and just let 'er rip
(Apex seals were replaced with something I could trust to 10k+ mis-shifts) It quit oil smoking but it still has enough blowby that I need to change the oil after a rallycross because it gets loaded with a ton of fuel. New side seals and cleaned up side housings will be on order this winter when I pull the engine apart to fix the coolant problem. And the exhaust port problem Anything you can do with a stock type intake manifold will not rev very high, so it doesn't make sense to try to stack the powerband to the right side of the tach. For all its fun my engine only makes noise over 8500, and even then it sounds very "flat" up there.
The powerband feels a lot like my 6 port did except there's just more of it everywhere. Good power until about 5500 and then it tacks on a bunch more and then starts falling off almost immediately. My streetported 12A also felt the same way, actually, with power/torque about the same as the 6 port 13B.
I guess what I am getting at is, if you are "only" looking for mid-high 14s and know how to drive a car, you should be able to do it with a 6 port with no problem. Focus on getting a good exhaust system on it, it's critical. (Look up GTORX7's thread on getting to 230whp, I think the exhaust and intake were worth 40 of that with the same engine)
I don't think there are ANY gains to be had in the throttle body, it is not the restriction in the system.
11-19-09, 06:13 PM
#12
exactly, GTORX7 did 230rwhp with street port and shortened cosmo intake. Sad thing is that some people struggle to make 200rwhp even with itbs and more agressive porting...
Exactly as Black91n/a said, that 230RWHP is on a 4 port motor- the 6 port motors really do struggle to make it to 200RWHP.
Exactly as Black91n/a said, that 230RWHP is on a 4 port motor- the 6 port motors really do struggle to make it to 200RWHP.
Agree, it is quite hard on a 6port engine. It can be done with T2 plates though.
And the most inportant piece of info, a fast NA will cost money, there is no other way around it.
11-20-09, 08:09 AM
#16
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Thanks for the replies, I appreciate your guys insight. Like I said I don't need this car to be fast, but I just want to get it to the point that it is not the slowest car I own including my 5200 lb old crappy V8 pickup truck. From my experience with the many cars I have owned, 15s in the 1/4 mile is the minimum requirement for a fun car and 14s or better is even more fun. Just to have enough get up and go to exceed the speed limit now and then.
11-20-09, 12:12 PM
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two things "they" do is test a ton of stuff, and the bac valve is open
we seem to always run into this, its like east coast dyno's read higher or something. our spec e30's make 155ish on the east coast they make 165.
11-20-09, 04:50 PM
#18
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That's why I like 1/4mi trap speeds. If you know your vehicle's weight, you can get your peak crank HP within a remarably close margin of error.
Fuel pulsewidths, trap speed, and even Dynojet whp readings all point to power in the 200-210hp range. Now, if only I could make 210hp at 4000rpm instead of only at ~7800 Okay maybe that's extreme, but you get the idea.
I don't have a BAC valve. Datalogs show me down to 89KPa at redline. Every little bit helps! That is one of the things I was planning on doing, rig a huge valve (like a evap vent valve) to the BAC valve location and rig it to the same switch as my 2 step. Call it the "happy mode" switch. I could also rig it to a RPM window switch I have but that wouldn't give me the stall protection a really high idle would give. Stalling on course sucks when you cannot reach the ignition key when strapped in.
Fuel pulsewidths, trap speed, and even Dynojet whp readings all point to power in the 200-210hp range. Now, if only I could make 210hp at 4000rpm instead of only at ~7800
Okay maybe that's extreme, but you get the idea.I don't have a BAC valve. Datalogs show me down to 89KPa at redline. Every little bit helps! That is one of the things I was planning on doing, rig a huge valve (like a evap vent valve) to the BAC valve location and rig it to the same switch as my 2 step. Call it the "happy mode" switch. I could also rig it to a RPM window switch I have but that wouldn't give me the stall protection a really high idle would give. Stalling on course sucks when you cannot reach the ignition key when strapped in.
11-21-09, 12:29 PM
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12-02-09, 10:48 AM
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I ran a 15.45 @ 89mph with a crappy launch in my '89. It had a rebuilt streetported motor, stock exhaust minus a crappy catback the PO put on and an 8lb flywheel. I'm sure with an open exhaust and better driving skills I could hit 14's.
12-03-09, 01:10 AM
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A lot can be said about lightening the heavy drivetrain. Light wheels, sticky rubber. Light flywheel and a good clutch. Solid or the like motor mounts. Aluminum n/a hood (quite a bit lighter than the steel one) Then, these things run rediculous rich in factory tune. A good intake and exhaust will get the afr's into a reasonable territory for making some power. Keep the damn air filter out of the engine bay for the love of god. There are far too many threads of cooling issues to add hot intake air to the list. General wear items need to be checked/ replaced. Spark plugs, wires, fuel filter. Don't skip the basics. They can be decently fast, it just takes some clever tricks and time.