MNdude07 : 1990 Honda Prelude SI

[gloryaccordy]

Holy shit, that F series motor mount kit is a real game changer. I had this chassis considered down and out, but now it almost looks more fun than a BB

Coilovers available for it too hmm.

Wonder what brake options there are

VERY interesting build choice, looking forward to see what you have in store.

Why not the H though?

[steelbluesleepR]

Why not the H though?

because he has a good f22 with a bunch of bolt-ons already!

[mndude07]

Holy shit, that F series motor mount kit is a real game changer. I had this chassis considered down and out, but now it almost looks more fun than a BB

Coilovers available for it too hmm.

Wonder what brake options there are

VERY interesting build choice, looking forward to see what you have in store.

Why not the H though?

Well the 3rd gen Si like mine has basically the same brakes as the accord. 10.2 or so inch rotors all around stock. I'm putting the 11" rotors and ITR/wagon calipers up front. This requires shaving a few mm off the caliper bracket, and re-drilling the 11" rotors to a 4x100 bolt pattern. Fastbrakes.com are my go-to guys for this info, and they make front and rear wilwood big brake kits for later on if needed. I plan on having the car so light that it doesn't need huge brakes though.

As for why the F and not the H, there are a few reasons:

I have a very healthy, strong F sitting in my wrecked CB7 that is free.

The F22 has a better flowing head and even if I went H I will ultimately have a cam so wild that vtec would be eliminated anyways.

The F22 is a lighter engine.

The F22 has a lighter valvetrain/rotating assembly, so while the raw power may not be quite as high initially, the engine's acceleration should be better.

H22's tend to make more power, but they are slugs out of vtec. The F is much better for DD and autocross because it has a longer stroke and has less mass in the moving components overall. That's one thing alot of people overlook. Its not just how high your motor revs or how much power it makes, its how fast it gets there too. F=ma ---> F/m = a, so with a constant force on the piston, a lighter mass yields greater acceleration.

[steelbluesleepR]

hey man, i just found some slotted 92-96 vtec prelude rotors that have already been drilled for 4x100 on a local board. the guy wants 100 for them


if you're interested, let me know and i'll get you in contact

[gloryaccordy]

Well the 3rd gen Si like mine has basically the same brakes as the accord. 10.2 or so inch rotors all around stock. I'm putting the 11" rotors and ITR/wagon calipers up front. This requires shaving a few mm off the caliper bracket, and re-drilling the 11" rotors to a 4x100 bolt pattern. Fastbrakes.com are my go-to guys for this info, and they make front and rear wilwood big brake kits for later on if needed. I plan on having the car so light that it doesn't need huge brakes though.

As for why the F and not the H, there are a few reasons:

I have a very healthy, strong F sitting in my wrecked CB7 that is free.

The F22 has a better flowing head and even if I went H I will ultimately have a cam so wild that vtec would be eliminated anyways.

The F22 is a lighter engine.

The F22 has a lighter valvetrain/rotating assembly, so while the raw power may not be quite as high initially, the engine's acceleration should be better.

H22's tend to make more power, but they are slugs out of vtec. The F is much better for DD and autocross because it has a longer stroke and has less mass in the moving components overall. That's one thing alot of people overlook. Its not just how high your motor revs or how much power it makes, its how fast it gets there too. F=ma ---> F/m = a, so with a constant force on the piston, a lighter mass yields greater acceleration.

Sounds good. I don't know that I agree w/the rotating assembly/valvetrain differences making for significant differences, but I can def attest to the F's better low end tractability. There's something that feels a little synthetic or unresponsive about damn near every H I've had or driven that was not the case w/the Fs, esp on the low cam. Could just be mental though. In any case this is def an interesting project... sophisticated suspension, small footprint, big torque. I looked up the weights and was a little surprised, thought these were a lot lighter. No biggies though, looking forward to the outcome anyway

[mndude07]

hey man, i just found some slotted 92-96 vtec prelude rotors that have already been drilled for 4x100 on a local board. the guy wants 100 for them


if you're interested, let me know and i'll get you in contact

Thanks man, but I can actually get them cheaper through fastbrakes. Also, I'm not sure if its the vtec rotor that needs to be re-drilled. It might be a 11" rotor from a different car. I'll have to confirm that.

[mndude07]

Sounds good. I don't know that I agree w/the rotating assembly/valvetrain differences making for significant differences, but I can def attest to the F's better low end tractability. There's something that feels a little synthetic or unresponsive about damn near every H I've had or driven that was not the case w/the Fs, esp on the low cam. Could just be mental though. In any case this is def an interesting project... sophisticated suspension, small footprint, big torque. I looked up the weights and was a little surprised, thought these were a lot lighter. No biggies though, looking forward to the outcome anyway

Yeah, I personally would trade better engine response for a significant amount of horsepower if I had to. There's no point in a ton of power if its not usable. Also, whats the weight you looked up? The SI has power windows, sunroof, cruise control, a/c, etc. while my DX cb7 has manual everything and on paper the prelude is still about 150 lbs lighter. According to the OEM Honda shop manual I have on pdf for the prelude, my model weighs 2608, and thats with no 4ws but with an automatic transmission. I want the car down to 2300 at least. Thanks for the comments.

[gloryaccordy]

I found the specs in some thread on H-T

Dropping 300 is def doable if this is gonna get gutted. But don't be afraid to put some smart weight back on for chassis reinforcement. Definitely tuned to this, keep us posted.

[mndude07]

I found the specs in some thread on H-T

Dropping 300 is def doable if this is gonna get gutted. But don't be afraid to put some smart weight back on for chassis reinforcement. Definitely tuned to this, keep us posted.

Yeah, an autopower roll bar is high priority after what happened with the CB7, and ESP strut braces if I discover that I need them.

[mndude07]

Megan Racing has additional coilover info added to their site...along with damper curves.




This makes me a little worried about running Megan Racing. I'm going to call them and see what they were thinking when they designed this valving. A1 is rear, A2 is front. Adjusting between full stiff and full soft seems to have a pretty good amount of crosstalk between rebound and compression, which is not good since these are supposed to be single adjustable, fixed compression dampers. Also, the digression knee is around 0.5in/sec, which is really low. I'm not sure what the damping ratio target was, but dampers like this should cause the setup to be a bit on the bouncy side I do believe. I don't like the way it looks. I really hope I can somehow get a Koni, Bilstein, or AMR under the car....

[gloryaccordy]

Low speed/mid speed damping will be weak, high speed damping will be stiff.... yea sounds like a shit time all around lol.

[mndude07]

Low speed/mid speed damping will be weak, high speed damping will be stiff.... yea sounds like a shit time all around lol.

Yeah, I don't know if they're on crack or what. If they can justify why they're like that, then I might still go with them depending on what they say. It also depends on the Koni, Bilstein, and AMR situation as well.

[mndude07]

I'm going to rip my hair out trying to get a decent shock under this car! Argh!!!
I have to make more phone calls tomorrow, but I've made some more progress. I'm on the search for some old Koni yellows...

[HondaGuy1212]

I have a real soft spot for the 3rd gen Preludes. The low hood and sleek dash has a definite race car attribute. If I could find a mint 4WS Si, I would be a happy guy. Your plans look great. subscribed to this thread. : )

[mndude07]

I have a real soft spot for the 3rd gen Preludes. The low hood and sleek dash has a definite race car attribute. If I could find a mint 4WS Si, I would be a happy guy. Your plans look great. subscribed to this thread. : )

Thanks man! Hopefully I don't disappoint.