7 replies to this topic

[XenoVibe]

I dont know as much about CRXs as I'd like to but this winter I wanted to begin this project, a 1st Gen CRX built for weekend AutoX/Drag that still retains DD driveability. My goal in mind is roughly 250whp, decent torque across the powerband and perhaps a coilover setup or some form of upgraded suspension from t-bar.

So basically, Im asking if the cost outweigh the benefits for running a B20Z VTEC swap as opposed to a B16B or D16a1/ZC1 for the specs I am aiming for? Should I forget about going the coilover setup route because of the cost for fabrication to increase structural integrity? Which way will save me the most time, money and headache?

The swap guide on here only stated B20A/21A series which isnt much of a B-series to begin with and the other B-series list only talked about 1.5 / 1.6L, which it will partly be, but Im not certain of clearence issues due to the B20Z having larger dimensions.

Edited by XenoVibe, 21 October 2010 - 03:24 AM.

[1986_crx_si]

If I recall correctly, a couple members here have b20's in their rex's. I am confident that you could fit this in there, and I can't see how it would be more difficult than any other b series swap.

With the specs you are aiming for, the b20 will put you closest, before needing any mods. Aftermarket parts are plentiful for any b series, but not so much for the D.

There has been discussion on coilovers, however the general consensus is that it is not worth the fabrication hassle and time, plus the risks involved with adding the extra strain to the other suspension components.

My final opinion for the least headache and bang for buck: Drop in the B20Z. Strengthen internals, I/H/E/C, P&P intake and exhaust manifolds, gasket match, larger TB, lighter flywheel, valve job, bump compression and fuel delivery, and tune it. That should get you close to you destination. Or just do internals and boost it to 10 psi.

Hope this helps!
-Aaron

[Screech]

I've been happy with my stock B20Z, so stock I still run the PHK ecu on it. Lots of torque for Honda 4cyl. I'm planned some exhaust updates as mine is currently plumbed from the stock manifold then though a modified A-pipe and CR-V cat into the Civic's stock "cat back". VTEC really would be more of a hassle to me as the engine with near stock exhaust and a LSD has traction problems in 1st and 2nd if you just give it the gas. Even in 3rd I can free the tires having a hard time holding on. And have found that in 4th at 60mph if passing to go light on the gas while switching lanes due to spinning on the painted lines. So all the extra cost and such to get more power that will only have use for 4th and 5th. Only going to really use either of those gears if you're at the drag stripe or on a nice big road course. I will admin that with some r-comps lower gears would be more use, I've not been lucky enough to find out yet.

I would say get the B20Z in there stock, try it. then decide once you seen what it will do in your car what it still needs. I don't think it would be too hard to swap the head and add the oil lines while in the car.

[hondaguy72]

Even a stock b20 would motivate this chassis with authority. I wouldn't use a b20 in more than a lightly boosted setup (6psi) due to the block design which tends to crack under high boost and high rpms. B18b/b18c blocks are more stout for the high boost/high rpm. The b18c comes with a main suport and was designed from the factory to spin to 8k which you would need to generate that kind of power.

All said, I'd do a b20 with a prepped head shooting for around 180-200hp at the flywheel. The torque curve would be optimal for a autoX car. That would put the power to weight at better than 10lbs per hp, an extremely fun territory. (basically agree with screech+86)

Edited by hondaguy72, 21 October 2010 - 09:11 AM.

[zakats]

HOW MUCH MONEY DO YOU HAVE TO WASTE? Seriously.

btw, I wrote the swap guide. I listed b20a's as a no-go; the crv b20's (b20b, b20b#, b20z4) are all viable options and are the 98% same, externally, as the LS's. B20's don't last too long @ high rpm, you may consider an LS instead- depends how nice you are to your engine.

[kaymo]

ok you are talking about autoXing this car, but are you trying to be competitive? you first need to look at the rules and figure out what class you are trying to run in. changing the suspension to full coilovers would either require major reinforcement or perhaps even rebuilding in tube frame. if you have the time and money go ahead, but dont forget that this type of modification is going to probably put you in the same class as the highest end cars. you might be the fastest honda on the autoX course, but you wont be in the same classing and you will be instead running with full custom built autoXers that make you look bad.

how much autoX experience do you have? its important to learn to drive a slow car quickly, instead of learning to drive a fast car and not run it off the course. gradually building up your car has many benefits VS completely overhauling your car to what you THINK will make it better. perhaps you would spend all the time and money to build your full coilover setup, and someone in a normal suspension 1g CRX comes along and waxes your times with it. how upset would you be then? then you would have butchered your car and spend a lot of money to take a step back

the stock suspension on this car keeps the weight very low VS coilovers which has the weight higher. aftermarket torsions and shocks can give you a very competitive car without changing your suspension geometry that will rocket you to the top of the autoX classses. you can do your swap but keep in mind in autoX, weight is the enemy! check out the weight of the different swaps and find the one that gives you the most bang for the weight. also keep in mind power bands, transmission gearing, and redline. at autocross you spend most of your time in first and second gear, probably close to redline. if your motor isnt designed to be spun up at redline all the time (like the b20) you could be looking at expensive failure quickly



my STOCK 87 crx SI with STOCK suspension and STOCK ride height, stripped out with slicks and tokico blues, big autozone air filter and 2 inch side exit exhaust had no trouble SPANKING evo's and sti's at an SCCA autoX with a good driver. even the FULLY prepped (teins, IHE, slicks+slammed) 2g SI had a hard time even getting CLOSE to the little REX's times. no one believed it was the ORIGINAL POWER PLANT

you should fix the car up to best stock condition and autoX it that way to find its weaknesses. consider things like a bump steer kit and aftermarket torsions before you consider gutting the whole suspension



whew im done

[regularguy]

i agree with kaymo- as soon as i bought my 85 si a couple months ago, i was looking for an integra for a swap. i was convinced to spend money on a tein set first and foremost, and i am happy to say that it will probably remain the best money spent on the car, period. i can only try to remember what my last 1g was like, as that was about 8 years ago, but i know that the current car drives like a properly setup autox car, and thats saying a lot for a car with such a strange combination of suspension and chassis/engine parts.

for autox, i would go with previous recommendations and just make sure that the stock engine is up to par- find a dyno and make sure of it. it wont cost a lot if you go to a reputable shop with reasonable rates and operators. my first pull showed 76hp, and because pretty much everything is stock, the only thing i could do was bump timing. first adjustment showed a consistent gain across the board with 89hp peak. the second adjustment went to 88, but everything below 5000 gained a few hp. the dyno i used is known to show about 5-8% lower than comparable engines elsewhere, but the gains are solid figures. maybe i should look into some springs for my distributor....

next money i would advise spending would be, of course, tires. a6s come in 255/40 13s, and although they wont fit under stock fenders, thats where an autocross car needs attention the most. no matter what you do and how much power you have, you will need good tires and suspension to do well. 250hp in a car under a ton is absolutely useless without huge rubber. i even found out that although i could have used more power in certain parts of the course, i was physically drained from having to turn the wheel back and forth so fast and so hard. im used to racing my dc2, and i can say that both power steering is a godsend for tight courses and 280hp even in a heavier car with hoosiers is a lot to handle. the edge gets so high that it seriously gets scary carrying big speed into a turn. brakes, 275s, and a whole revamp of the suspension on the car would be necessary to properly utilize the power. toss that combination into a 1g (ive contemplated it), and its either crazy fast or just a crash- and most likely the latter.

drag racing is a whole different animal- a properly setup drag car wont autox well, and vice versa. it boils down to which is more important, how you want to bias in between the two, and how streetable the car must be. i would do suspension, tires, and an engine refresh first. then autox it and see where you stand. then add nitrous and drag slicks and turn some times. after all of that, you will have a decent idea of where you want to go with the car-

[XenoVibe]

Wow thanks everyone for the useful information! very precise and detailed responses. you've given me quite abit to think about.

Ive got 6g to spend on this project. As for the B20Z VTEC well it would cost $1200 whereas B18C 92-95 GSR motor costs a few hundred more and even more for turbo/manifold but the B18C lacks torque without a turbo. May not sound like much but for the cost of brake, suspension, and drivetrain upgrades it made the difference.

No, I don't have much AutoX experience but this project isnt meant to be a competitive build just a daily driver with a playful power to weight ratio for the weekend when we setup a few dozen pilons at an empty lot .