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The Eagle (umm, more like Big Bird) has landed. The tandem team from Reliable Carriers showed up on schedule and carefully unloaded the CRX from the top deck. There was some other interesting hardware on that truck, including a pristine original Model T that was being delivered to the grandson of the current owner. The previous owner to that – the current owner’s grandmother - was the original owner, and the car had never left the family since new!

Plastic is Fantastic – Part 5, the Eagle Has Landed

by Jonathan Spiegel

In installment 4 of the Polystrand GT-Lite Project, we made our deadline and had the car ready for a couple of trade shows. Granted, we had some issues that we needed to take care of – we checked the rulebook, and it turns out the wheelbase was a bit too long – and the rear of the unibody was found to have been pushed over to the left about an inch from an on-track incident in the CRX’s storied past. In addition, since we made so many changes, the rear portion of the cage was no longer tied in to anything structural.

Catch up on the rest of our Polystrand GT-Lite Project

Here’s a shot of the original rear suspension system looking down through the hatchback. The dark blue beam going across is the axle beam, and the yellow bits are the Mumford linkage.
A view of the original system from below.
Here’s a good look at the original cage work with the original suspension removed. The two big vertical tubes were the coil spring towers – the coilover shocks in the rear were mounted inside these tubes.

As with most amateur racing endeavors, life, work, and other projects inevitably took some priority, but, after locating some shop space and equipment, we were able to bring the car back from Detroit, and start digging in in earnest once again. Besides the structural work that needed to be done, we’ll be upgrading the driveline as well. The vintage mid-80’s 3-valve Honda EW motor, while still capable of being a strong contender because of the weight breaks allowed, is being replaced by an Acura B18 LS series motor for several reasons. First, and foremost, for reliability - because class rules require an intake restrictor, in this case a tiny 22.5 mm in diameter, the rpm ceiling is dramatically reduced. Calculations show that airflow will level off at about 6300 rpm, so power will start to fall off pretty rapidly at that point. At those rpm levels, wear and tear will be minimized, and many racers running restricted engines in the GT classes report racing two or three seasons between rebuilds, and seeing no appreciable wear when they finally do tear down. The second reason is simply that there’s a very strong aftermarket for these motors, and it will allow us to easily run a pretty sophisticated engine management system – the AEM Infinity – which is key to making good power above the choked flow rpm induced by the restrictor. Coupled with parts from Brian Crower and Action Clutch, we should have a driveline that makes good useable power with minimum fuss, and at a reasonable cost.

I’m a big fan of centralizing mass in a race car – keeping weight down low and centered in the vehicle makes a big difference in the handling and performance of most any vehicle, and our CRX is no exception. While not an advantage, the switch to B18 power requires us to add well over 200 lbs to the race weight of the vehicle. The bright side of this is we can put this extra weight where we can benefit from it the most.

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Comments
SquishyPanda
SquishyPandalink
Wednesday, September 30, 2015 5:32 AM
I noticed that the new crossmember (the one salvaged from decomissioned equipment) doesn't go all the way to the passenger side of the main hoop. Is this just obsessive weight saving and it's not structurally necessary?
Jonathan Spiegel
Jonathan Spiegellink
Wednesday, September 30, 2015 1:23 PM
Not obsessive weight save, but not structurally necessary either. With the downtubes and diagonal in place, any loads from the suspension will be easily handled.
Monkius
Monkiuslink
Wednesday, September 30, 2015 2:22 PM
Whaa!? Are the EW's header tubes paired 1-2, 3-4 or do I have crazy-eyes?

Also, a 1.5-way diff in a FWD? Do you like understeer during trail-braking? (Serious question.)
Monkius
Monkiuslink
Wednesday, September 30, 2015 2:24 PM
Nevermind the first question, I just looked at part one and noticed that the header is 4-1.
Jonathan Spiegel
Jonathan Spiegellink
Wednesday, September 30, 2015 2:46 PM
With the suspension setups I run, I don't really have any problem with understeer during trail-braking. Since we are allowed to run rear wings or spoilers, we can be aggressive on the rear stiffness because the downforce keeps us stable in high speed corners (where there is usually little or no trail braking), and allows the car to rotate easily in the low and mid-speed stuff.
Supercharged111
Supercharged111link
Thursday, October 01, 2015 9:02 PM
I ran a Kaaz 1.5 way in my AE92 and it was magic. FWD loves to oversteer on a greedy entry.
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