88 Civic HB aerodynamics

[K2e2vin]

Does anyone have info on the 88 Civic hatchback? How does it compare to the 92-95 Civic hatchbacks and the CRXs? I'm curious as I'm looking to improve the aerodynamics(for racing purposes), but seems like no one does anything with this generation of Civic hatchbacks.

[Christ]

Aero doesn't really care what car you have... take a few mins and search around, you'll find plenty of information about aero in general, and once you've learned about it, you can properly apply it.

[tanjulio]

I have been asking the same question for my 1990 Civic Standard 4spd...
i have taken this car to Laguna Seca and the results were pathetic..lap times were over 3 minutes.. old stock engine and tires gave up on me after only warm up 4 laps...

if you do not have B series engine...or a turbo on your rebuilt d series engine you will not be competitive,
unless you are competing with similiar slow cars...
u have the lightest model year and if you have the stock engine it's slow..
Do you have the stock DPFI or did you convert to MPFI???
changing to MPFI will net 10 -15 % more power on stock engine..

I have thought about more downforce and less drag, especially since these cars stock are seriously underpowered.. SO:
i am going to build a Kammback and undertray for my hatch and hood vents.
and eventually change to a 5spd transmission...

[Christ]

Originally Posted by tanjulio

I have been asking the same question for my 1990 Civic Standard 4spd...
i have taken this car to Laguna Seca and the results were pathetic..lap times were over 3 minutes.. old stock engine and tires gave up on me after only warm up 4 laps...

if you do not have B series...or a turbo on your d series engine you will not be competitive, unless you are competing with similiar slow cars...
u have the lightest model year and if you have the stock engine it's slow..

I have thought about more downforce and less drag, especially since these cars stock are seriously underpowered.. SO:
i am going to build a Kammback and undertray for my hatch...
and eventually change to a 5spd transmission...

This not true in theory or in practice... the D-series engine is a prime contender when cost/performance are considered together, and boost is not a requirement. 200+ HP is doable on an all motor application with proper build and tuning, and with boost, 400 and up has been done on the stock crank.

The first things that you do with a D15B1 to increase power AND efficiency are to upgrade to a 5 speed from 4 (not really necessary, but better gearing choices), swap in the cam from a D15B2 or D16A6 (basically same, offset timing for A6), and install MPFI and a header. The engine in stock configuration is mild and choked, and doesn't perform well at all in either department. 20 HP and more mid-range torque is gotten just by changing the cam from B1 to B2 models, without further tuning. Swapping to MPFI gives approx another 8 HP, bringing you up to ~100 at the crank with all OE parts, and still no tuning done, and only a few hours' labor.

Those figures assume you have a nearly fresh engine which is still capable of making OE performance.

The header takes your 1.5L engine beyond Si and Wagon HP figures, and often further increases mid-range torque and responsiveness. The OE intake is good enough to support advanced driving even with those upgrades and a paper filter, so no point in changing it. You only serve to make a loud car with less low-end grunt by doing so, but a WAI could save you fuel.

This really is the wrong forum for these types of discussions, though... if we're going to talk about aerodynamics, we're OK, but engine performance is best left to forums which are attuned specifically to that side of vehicle modification.

[tanjulio]

Originally Posted by Christ

.

This really is the wrong forum for these types of discussions, though... if we're going to talk about aerodynamics, we're OK, but engine performance is best left to forums which are attuned specifically to that side of vehicle modification.

So, what advice was offered for aero????

again, i have asked aero mod questions for downforce/ reducing lift, and i have only been told to search the other links to get ideas and basic information.. nothing specific for this car because noone with this specific model has documented it here..
THE focus of this website is increasing fuel efficiency...
Please note;
Other ppl at ecomodders get off topic,, many times individuals complain about something someone said OR simply Disagree.. and get off the topic...????

I simply said that if K2e2vin wanted to race he would probably be better off changing the engine...instead of aero mods
because
I have never seen these cars with less than 150,000 miles,, and that is not fresh.. and very low hp..

Again, 100 hp is nothing great. i had an 89 si and it was not fast... slow... .
believe me, i have been at a road course with corvettes, wrxs, evos, minis and mazda wagons..
you will need a modified b series engine or turbo'd rebuilt d series to keep up with these other cars at a 'road course'
OR
enjoy slow lap times with a tired d series ....

Modifications to your car depend on your goals....
I want more power and much more MPG....
The website is helpful but one has to keep searching... and finally I have the answer to my goals...

Kammback with tranny swap is probably the best option for my car and my goals..

[Christ]

Originally Posted by tanjulio

again, i have asked aero mod questions for downforce/ reducing lift, and i have only been told to search the other links to get ideas and basic information.. nothing specific for this car because noone with this specific model has documented it here..

You won't find information specific to a given vehicle, in most cases, because as I noted above, aerodynamic forces could really care less what you're driving.

Do yourself a favor, and do a little research on aerodynamics in general, then apply your newfound knowledge to your vehicle. Document it if you care to. But understand that there is no end-all be-all to aerodynamics on a per-vehicle basis, nor will there ever be. What works for one person's car may not work for another car, or it may, and until you understand why it works, you'll never know if it will truly work for you.

Don't guess at it - you'll only disappoint yourself.

[tanjulio]

Understood! and there is no way i will ever claim to be an expert or knowledgeable about aerodynamics..

I will take what other ecomodders have done as guidelines for my project...
and it is true that some of the same mods in different vehicles have netted different results...

I have tried to learn from other's mistakes and successes...
we are fortunate to have this forum so the brave ecomodders can document.

and listened to their advice....

I did learn that hatchbacks love kammbacks...
I really like this smiley on the turtle... thats' how i feel when i drive my civic...
faster... faster .. dang it..

[K2e2vin]

I'm curious what others are doing; especially for the upper rear section of the car. Sloping the rear end like the CRX would be nice but that's more work I want to do and would permanently "ruin" the car; preventing it from competing in specific race classes.

Right now, one thing I thought about is replacing the side windows with Lexan, and NACA ducts the expel air to the rear; probably through lexan rear windows. For the bottom though, would it be best to run a low diffuser or have it come up(bumper cut to allow air to exit higher)? Exhaust dumps in the middle so that's not an issue.




Engine is not a concern. It has already been swapped to another D-series motor(JDM D15B VTEC), and is currently being built(13.5:1CR, ITBs, short DOHC ZC trans. w/1st gear+ZXi FD+LSD, Bisimoto header+valvetrain, etc.). Power goal is +170whp which should be plenty.

I actually got ~57mpg highway with the car and a unknown-brand camshaft in the D15B VTEC along with a short transmission(DOHC ZC with Si 4.25 FD); I cruised in 5th at 4000rpm(about 70mph).