Fit Engine Modifications, Motor Swaps, ECU TuningReference Library for Engine Modifications, Swaps and Tuning
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So, been thinking and reading stuff the past couple days...
splice into the dbw wiring and use 2 umm TB actuator assemblies/motors...whatever. Or try find a vehicle with a larger one that'll somehow work cause I guess the one on the fit may not really be able to open 4 butterfly's/TB's at once lol, so I figure it could atleast open 2 cause 1 on each TB would be ***. Then come the MAF sensor. Could use a manifold and it'd prolly be fine but why have ITB's if you can't see em...lolz. Maybe you could splice into the MAF wiring also...(?) and rock 2 or 4...4 would prolly be safer.
I had another idea but i can't remember it.
But yea, considering we apparently can't do any tuning with the ECU those are the work arounds I've thought of. I think I also seen a couple builds/swaps from dbw to a standard linkage.
Definitly wish I had more resources.
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if yer lookin for a Fit...$13.5k n an 08' VBP gd3 is yours. Or $4k and a 94' delsol is yours
yumminess
1993 Buick LeSabre - most comfy car...ever.
2008 Honda Fit - funnest and most versatile car...prolly ever.
Most ITB setups are tuned to run via throttle position, and they don't use MAP. Even on a vac log it's rare for people to see more than 10-11 in Hg at idle whereas a typical plenum - single throttle setup you get that vac under cruise, and about 20 in Hg at idle.
What makes it bad is that with just a little throttle you lose most all of the vacuum, and a MAP would tell the ecu it's at WOT but really you're only at 25% on the throttle.
Yes I'm going to compare to the d-series again (it's valid because both are long stroke, small bore, low r/s ratio, and have a conservative cam). On a d, ITB's are generally considered worth the PAIN in the BUTT they are to tune after compression is around or above 12:1; when the cam that when installed in a non-vtec setup sticks you with a 1500 rpm lopey idle; when the 2.25" collector on your 4-1 header sits behind where the cat used to be; and when you decide you're going to take advantage of the better fuel atomization above 7500 rpm when you stick the injectors back by the throttle plate instead of right before the head.
When the head doesn't need the wicked airflow and resonance of the ITB, or rather can't use it, the plenum setup usually wins because you can actually tune it and in most cases make more power with it. It's real easy to mess up taper and angle on the runners and kill power.
If you want to read lots of good stuff, there's been LOTS of diy development on ITBs on d-series.org.
Most ITB setups are tuned to run via throttle position, and they don't use MAP. Even on a vac log it's rare for people to see more than 10-11 in Hg at idle whereas a typical plenum - single throttle setup you get that vac under cruise, and about 20 in Hg at idle.
What makes it bad is that with just a little throttle you lose most all of the vacuum, and a MAP would tell the ecu it's at WOT but really you're only at 25% on the throttle.
Yes I'm going to compare to the d-series again (it's valid because both are long stroke, small bore, low r/s ratio, and have a conservative cam). On a d, ITB's are generally considered worth the PAIN in the BUTT they are to tune after compression is around or above 12:1; when the cam that when installed in a non-vtec setup sticks you with a 1500 rpm lopey idle; when the 2.25" collector on your 4-1 header sits behind where the cat used to be; and when you decide you're going to take advantage of the better fuel atomization above 7500 rpm when you stick the injectors back by the throttle plate instead of right before the head.
When the head doesn't need the wicked airflow and resonance of the ITB, or rather can't use it, the plenum setup usually wins because you can actually tune it and in most cases make more power with it. It's real easy to mess up taper and angle on the runners and kill power.
If you want to read lots of good stuff, there's been LOTS of diy development on ITBs on d-series.org.
You make a good point, but again the head on the l15 isn't nearly as capable as the dseries because of the port size. Dseries are capable of over 200whp with itb's, the l15 is sadly, nowhere close.
Another thing some of you need to realize is that itbs, like polaski was saying, are not DD friendly. They are hard to tune, and dbw won't really work correctly with them. Show factor is about all their use would be.
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Originally Posted by AP Kreuzercute car something my gf would drive.
Whtsjdm Maybe not drive, but she loved "Refresh mode"
You make a good point, but again the head on the l15 isn't nearly as capable as the dseries because of the port size. Dseries are capable of over 200whp with itb's, the l15 is sadly, nowhere close.
Another thing some of you need to realize is that itbs, like polaski was saying, are not DD friendly. They are hard to tune, and dbw won't really work correctly with them. Show factor is about all their use would be.
bisi's ITB 230whp d15 wasn't your normal D. Compression was above 15:1, the cam was HUGE, the ports were big enough to make a mopar fan envious, its idle was around 2200 rpm, redline just over 9k, etc etc.
All the other 200+ whp setups I've seen were in the 15:1 comp range and used carbs. Most people get stuck around 150 whp with the occasional 170 whp gsr killer. It's getting less and less popular because for about the same cost you can go FI and be in the 400+ whp range.
Too bad we can't port the L15 head. Need a custom cast 20v head . There are people with the small valve y7 heads above 250 hp, those can't be much bigger than an L15's
Don't give up hope yet... 5 years ago when I got into modding hondas there was a big stink over Rexinre's edelbrock setup and the 238whp he got it up to. It blew up fairly quick but at the time most were stuck at 190 whp due to lack of tuning options. No one cracked the ecu until later (turboedit, then uberdata!).
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08 VBP L15A1 MT stock
Last edited by polaski; 12-31-2008 at 12:11 AM.
Reason: keyboard battery keeps dying
yea, with the d15 couldn't you swap the i think y7 head on the hx for a y8 and be perty happy for really cheap lol.
I WANT A DIFFERENT HEAD
I want something "different" that people will look at and know that some work was put into it to get it right. Along with the fact I want to stay n/a...yea.
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if yer lookin for a Fit...$13.5k n an 08' VBP gd3 is yours. Or $4k and a 94' delsol is yours
yumminess
1993 Buick LeSabre - most comfy car...ever.
2008 Honda Fit - funnest and most versatile car...prolly ever.
They pretty much all swap out. There's been z6 heads on a6 blocks, y8 heads on y7 blocks, y8 heads on y5 blocks, z6 heads on b2/b7 blocks, d15b vtec heads on anything non-vtec, y8 head on b7 if you want compression, and for the weird one, y7 heads on y8 blocks
Just the dohc zc doesn't match anything, and sometimes you run into trouble with valve reliefs or lack thereof on the 8v d15b1/b8.
I know what you mean about staying n/a-- fewer parts to break, lower temps, linear power, all that good stuff.
If I had to guess, with parts computer harness fabrication whatnot you'll need... ballpark $1500-3000 for a DIY ITB setup, the most of that being a standalone ecu. (you could probably save some dough if you can get ectune to do it, but it won't be easy.)
If it were me, I'd get a weaponR mani and chop off the plenum and part of the runners; use a cbr939?600? itb setup; reverse the tps (it's backwards); convert to cable throttle; mount the injectors by the throttle plates and use the holes in the head for link to vacuum box; put the velocity stacks into a 3L plenum box with a k&n filter on the end; have runner length at 22" valve to stack for a rough 2nd harmonic from 5300 rpm to redline; weld a longer-tube 4-1 header into an RSX cat, then 22" magnaflow resonator into a knockoff twinloop muffler; tuned on an AEM computer with the stock ecu as piggyback (which would probably take 6 months plus to work out the kinks). All in all it would probably be good for 105, 110 whp maybe. Throttle response would be its strongest suit, so it would be good for autox, but past that, hardly worth the effort.
They pretty much all swap out. There's been z6 heads on a6 blocks, y8 heads on y7 blocks, y8 heads on y5 blocks, z6 heads on b2/b7 blocks, d15b vtec heads on anything non-vtec, y8 head on b7 if you want compression, and for the weird one, y7 heads on y8 blocks
Just the dohc zc doesn't match anything, and sometimes you run into trouble with valve reliefs or lack thereof on the 8v d15b1/b8.
I know what you mean about staying n/a-- fewer parts to break, lower temps, linear power, all that good stuff.
If I had to guess, with parts computer harness fabrication whatnot you'll need... ballpark $1500-3000 for a DIY ITB setup, the most of that being a standalone ecu. (you could probably save some dough if you can get ectune to do it, but it won't be easy.)
If it were me, I'd get a weaponR mani and chop off the plenum and part of the runners; use a cbr939?600? itb setup; reverse the tps (it's backwards); convert to cable throttle; mount the injectors by the throttle plates and use the holes in the head for link to vacuum box; put the velocity stacks into a 3L plenum box with a k&n filter on the end; have runner length at 22" valve to stack for a rough 2nd harmonic from 5300 rpm to redline; weld a longer-tube 4-1 header into an RSX cat, then 22" magnaflow resonator into a knockoff twinloop muffler; tuned on an AEM computer with the stock ecu as piggyback (which would probably take 6 months plus to work out the kinks). All in all it would probably be good for 105, 110 whp maybe. Throttle response would be its strongest suit, so it would be good for autox, but past that, hardly worth the effort.
that HP goal is way low, the L lacks flow but isnt that sad. people have made 115whp with a full WR setup and i believe someone made more then that.
My manifold setup made 100whp with just that and an DIY intake, stock header stock cat, stock exhaust... i think 120 is easily within reach if you have these parts and have a good tune. Then theres making a custom cam ground, to make a little more power then that.
However i agree with you that a well designed plenum intake manifold with ONE TB will make just as much power as ITB's on this motor
you guys are on the right track here. d16's are not much bigger than the l15, it makes more power and can be had for a measly 550$for the JDM d16zc with low mileage. i've been swapping these into USDM civics for years now. its great, reliable motor with spunk and tons of tuning options. i think a dual cam zc with turbo and head work would yield around 200hp or even a single slammer Y8 for the v-tec. which is plenty for anyone that wants to auto-x or rally their Fit. (did i just say rally cross and fit in the same sentence?)
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Last edited by wontfit; 01-01-2009 at 04:49 PM.
Reason: im a retreaded tire
also, another option. if you can't open up the head, then increase the RPM's. has anyone balanced and blueprinted a crankshaft yet? if so, i wanna know the redline on it. this is what they do in F1 and INDY.
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Last edited by wontfit; 01-01-2009 at 04:52 PM.
Reason: i play with myslef.
i have been talking with the guys at spoon and they have said they did really nothing to the head except open the combustion bowl a little. their big secret is balancing the internals to perfection. their idea for tuning their fit is reliability and handling rather than balls out power. i think that is the ideal way to tune the l15 since it wont make fast hp numbers. just focus on handling is the way to go.
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high roller #7
Quote:
Originally Posted by dewthedew
Yeah, I was thinking about you when i made that post. You're insane and I say go for it! you'll have the most badass fit ever.
also, another option. if you can't open up the head, then increase the RPM's. has anyone balanced and blueprinted a crankshaft yet? if so, i wanna know the redline on it. this is what they do in F1 and INDY.
You realize this will do nothing right? That faster the motor spins, the more air that needs to flow. If , like we discussed the L15 is very limited to flow, raising the rpm will do nothing but just spin faster making no more power and even lose power compared to peak HP.
Also, balancing the crank is only part of the equation, both the cam, and valve springs must be able to handle the increased speed. Most cranks can handle more RPM's to a reasonable level if they are close to being square(equal bore and stroke) However the L15 is a pretty over square motor at 73x91. Increasing the RPM would increase the piston velocities WAY to high, this would not be such an issue on a square motor like a b16 k20 etc. (F1 motors have a extremely UNDERsquare design with a huge bore and tiny stroke, of less then an inch, which is why they can rev so high),the head also causes the issues, the valve springs are not strong enough and the valves float at high RPM's
There are not many options for tuning the L15 for a NA setup for big power. The head just cant flow that well with a 45* valve angle. I havent looked that much into the motor, however already being an oversquare motor, giving it a larger stroke probably isnt an option. This just leaves oversized pistons, and possibly a little bump in compression though it is already a bit high in the 10.X:1 range
Ideally i think the best L15 NA setup would be a large plenum intake manifold, larger TB, simple intake, race header, 2" - 2-1/4" exhaust, with a custom grind cam, and oversized high comp pistons. Also the obvious tune with a standalone unit
that HP goal is way low, the L lacks flow but isnt that sad. people have made 115whp with a full WR setup and i believe someone made more then that.
My manifold setup made 100whp with just that and an DIY intake, stock header stock cat, stock exhaust... i think 120 is easily within reach if you have these parts and have a good tune. Then theres making a custom cam ground, to make a little more power then that.
However i agree with you that a well designed plenum intake manifold with ONE TB will make just as much power as ITB's on this motor
100whp with just an intake? That sounds too good to be true.
my friend said, he just doesnt have the time nor was it really financially beneficial for him. Takes a lot of time and energy to produce a one off piece like this
. There are people with the small valve y7 heads above 250 hp, those can't be much bigger than an L15's
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