DB4 Tunnels

[B17overhead]

Would like a pair of DB4 A spec tunnels.
Chuck Voboril
AZ
480-837-4531

[FWSchroeder]

I know Kris Keiser of K-Hill Motorsport has a new gelcoat DB4 Rear Deck and alot of other DB4 parts.
717-324-2758 he's due back in the shop 3-26.
www.swiftformulacar.com

[B17overhead]

Thanks-However, I think the last time I checked with Kris he didn't have any tunnels. The A-spec tunnels were not the popular ones-so looks like I might have a bit of scratching about to do.

Chuck

[B17overhead]

Has anyone even heard of the DB4 A-spec tunnels?

Thanks,
Chuck

[Steve O'Hara]

Never heard of them. To the best of my knowledge there were two types.... the original design and the update tunnels offered for the 1992 season. The update tunnels were crap and made the car much harder to set up. I ran the Pro series in 1991 and set lap records at Mid Ohio, Three Rivers and Nazareth with the standard shaped tunnels fitted with splitters. I was driving for P1 racing in 91 and we did the development testing on the new parts and none of the updates ever proved to be better than the original parts.
Steve O'Hara

[Paddy O'Brien]

Almost every DB4 I have seen has the standard tunnel configuration. After all it was good enough for Ralt to copy! Lateral tunnel dividers were a later addition and all seem to agree that they make the air work better. There were extension pieces added to the ends of the tunnels that I was told was for speedway/high speed use and it moved the downforce center to the rear. I have seen a couple of DB4's reciently that have had the slope of the rise at the rear of the tunnel reduced in an effort to keep air better attached, I think Wilcox has done that. Swift DB4 owners; lets not tell anyone but the SCCA skirt rules gives us a huge advantage over the 014/RT41 crowd, a creative mind could create a virtual full-skirt ground sucking vehicle out of a DB4. Of course then we would have to go to a rock hard suspension which would turn the most fun racecar in the world into a big go kart, but it sure would corner!

[Dave Welsh]

Algie Composites repaired the rear half of the right side tunnel on the DB4 I crew on. The repair was done in a mold. They did a great job on the repair. The repair cost $800, a new tunnel 2 years ago was priced at $1600. Carbon fiber and aluminum honeycomb was used in the tunnel, fiber glass for the outer panel As I understand, Algie has molds for everything but the engine cover for the DB4.

http://www.algiecompositesinc.com/

[B17overhead]

Paddy, your comment about skirt rules is interesting.

Are you referring to this?:

Movable or hinged skirts are prohibited. Flexible sidepod skirts are allowed on cars which have their primary load bearing structure (tub) constructed of ferrous or non-ferrous alloys. No part of the bodywork or suspended part of the car between the front and rear wheels shall extend more than one (l) cm (.3937”) below the horizontal panel forming the bottom of the chassis. Within the above restrictions, only wearable material (fiberglass, Kevlar, carbon fiber, high density polypropylene, Telflon, Lexan, or wood) may be attached to the side panels as a rubbing strip. Ceramics, plexiglass, plastic, and other materials which shatter or break-up causing hazardous track condition are prohibited.

The intention of this Section (17.1.6.A.1.g.11.) is to control ground effects on all cars by prohibiting “sealing” or bridging the gap between the bodywork and the road surface, and to do so in a uniform and consistent manner. Any means adopted to circumvent this intention shall automatically be regarded as a breach of these regulation"


I think that all this means is the allowable 1 cm below the bottom of the car can be flexible on metallic chassis cars.

[Paddy O'Brien]

yes, thats it

[RussMcB]

When I had my DB-4, I heard from several sources that the rules were (re)written to specifically allow a skirt advantage for DB-4's, to give them a chance to be competitive with newer cars. I never quite saw it in the written rules in a way that jumped out at me, but one of the sources was a comp board member who ran DB-4's, so it sounded like accurate information.

[Charles Warner]

The original rules that put the RT-5 into FA allowed them to run FULL skirts touching the ground. This was a hold-over from the Pro SV days. AFAIK that no longer is the case.

[Paul LeCain]

You can run the ground-touching skirts on an RT-5.

The DB-4 rule is that the skirt can be 1 cm. below the tub. For carbon-bodied cars, the rule is 1 cm. above the tub. I was never able to run a DB-4 with skirts below the tub. They scrape off and lift the wheels off the ground over curbs. We had the most luck with skirts just at tub level.

[swede9]

Would like a pair of DB4 A spec tunnels.

Just to help with this, in 1991 when Hiro Matsushiita purchased Swift Race Cars from Bill Fickling and Jim Chapman it was decided to update the DB4 rather than producing a completely new car. David Bruns looked at updating the underwings, front and rear wings, nose & nose box. Testing was done in the winter of 1991 with Bill Fickling doing most of the driving at Willow Springs. Conditions there at that time were less than optimistic and the Yokohama Tires were rather out dated having been made in 1990, so most of the testing was done with Goodyears as they were much more constant and came up to temp much better than the Yokohamas. Different wing configuration were tried along with a number of revised underwings, rub strips Etc. In the end the revised underwings seemed to be better at Willow, they were offered in a kit with the revised wings nose and nose box, however testing by other drivers at other tracks seemed to confirm a inconsistency problem with the underwings, which we now know that the revised tunnels would lose downforce at low ride heights. A VG (vortex generator) similar to the one used on the 014.a underwing may have helped solved some of this problem, also current shocks are much better at controlling ride height than what was available then. The rest of the kit, wings, nose, nose box where all shown to be better. Swift gave a refund to any one with the revised 014.a tunnels and destryed the ones that were returned. As David would say he could figure it out with a Wind Tunnel, which Swift was still 2 years away from completing. Only one DB4a was sold, it included the aero kit plus a Pi system, Penske 4 way shocks and a magnesium cam cover. The car sold for $62,500.
As far as skirts go, the best system we used in the Super Vee days was the spring steel skirts Ralt offered, they attached to the side pod vertically then had 2 45 deg bends so that the rub strip attached with sheet metal screws and would be changed every session. The spring steel would stay a 1 cm below the tub then on the track would get pulled down to seal the sidepod and would spring up going over curbs, this system worked the best of all the skirt option tried.
[FONT=Arial][SIZE=3] [/SIZE][/FONT]

[Steve O'Hara]

And to help a little more with the history....

The update side pods were first tested at Mid Ohio in the summer of 1991. I drove the P1 #8 car in standard configuration as the base line car all day while Jovy Marcelo started with the standard pods to baseline his car and then switched to the updated version in the late morning. As I recall (and keep in mind this was 16 years ago) Jovy ran 19.5s with the standard package before switching and never got in the 19s with the new pods. As the day wore on I dropped my times down to 18.5s and Jovy was in the 20s. Apparently the "engineers" didn't think the test results were reliable so more testing was done with Bill doing all the meaningfull driving in the winter of 1991/1992 and the conclusion was they were better so update kits were made available for the 1992 season. A few notes on that season... the P1 cars of Jovy and myself started the season at Miami in original configuration and I finished 2nd, .8 seconds behind Russel Spence in the new factory Reynard effort. Jovy's fatal crash at Indy prior to the second race of the season changed the circumstances at P1 dramatically and I ended up buying my own car and embarking on running my own program, returning to the series at Laguna later in the year. Chris Smith went on to win the title in 1992 with a standard configuration DB4 for most if not all of the races. At the start of the 1993 season P1 had Mark Dismore and Trevor Seibert in the cars with the updated wings and nose and original side pods. There were other Swift runners with the updates as well but I don't remember who and how many. I ran the standard components and was the highest finishing Swift in the first two races at Phoenix (2nd)and Long Beach(4th). I switched to a new RT40 for the third event and sold the DB4 but I feel pretty comfortable saying that there was never any convincing evidence that the updated wings and nose were faster than the original package but they did look more contemporary I should qualify my remarks by noting that the Pro series rules mandated the fairly hard compound Yokohama tires and the side pods were required to be a half inch (might have been 1cm) above the plane of the floor of the car. As such, the downforce levels of the original setup was pretty much optimum. The revised rear wing assembly could be set up to have a lot less drag than the original rear wing and it may very well be better for club racing where gummy tires and tighter skirt clearances are allowed.