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Boy, when it rains it pours. At New Hampshire International Speedway yesterday, our Opel racers had a rough going. Early on, Tom Drake's GT-4 Opel GT had its' clutch let go after about three shifts during the morning practice...ugh. Thankfully he still had his old flywheel and clutch in his tow rig, so I lent him a hand and he got it back together in plenty of time for the mid-afternoon's qualifying session, where he placed third overall and 1st in class (on slicks, in the rain!). Assuming no other incidents, it looks good for Tom to take his class win on Sunday's main feature race.

Ed Funk's ITB Opel Manta also had it rough. His wife was running the car in the "Volvo Historic Challenge" early on, and was black-flagged for smoke. Turns out when they swapped the tranny the week before, they overlooked installing a plug for the speedometer drive, and the oil was pushing out as the tranny heated up. We cobbled together a vent system in order to get Ed out for his run group in ITB, but the rear tranny seal started leaking as well....same result. So as of last night, Ed was waiting for a new rear seal to be delivered for this morning's racing session. Best of luck to him and his wife Stephanie during today's races.

Jim MacMahon probably took the hardest beating of all, at least to his ego! All day long it was rain on, then rain off, then rain on again. A lot of other drivers were constantly switching tires in an effort to be prepared for whatever the weather held for them. Jim made the choice to stay in his 'dry' racing setup, with the sway bars still attached and his Hoosier dry tires. Oops, wrong choice. It rained constantly throughout the run group, and Jim finished WAYY in the back of the pack, which means that Sunday he'll have his work cut out for him during the race, as he'll have to work through about 20 other cars to get to the front. He was about 25 seconds per lap off his normal pace!

Bob Legere
'Northeast Race Correspondent'




Jim MacMahon NOT enjoying himself....
 

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Discussion Starter #2
For those of you who aren't familiar with the other New England Opel racers, here's a photo of Ed Funk's ITB Manta.

Bob
 

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And here's Tom Drake's Opel GT (runs in GT-4 class).
I'm going to see about tracking down some other photos of other racers across the country so I can post them to this site. I know Bob Dennard has posted photos of his ITB GT, then there's Stan Czacki, John Mills (kicking ass this year BTW), Ernie Bello (Gray market 1978 Kadett C), Roger Wilson, Roger Lee and others that are either currently out of action or still being built.

Bob





Tom Drake's Opel GT
 

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wow it sure is nice to see some Opels out there on the Track


and Tom Drakes famous GT4 car

maybe you could fill in the good people in on Tom Drakes Car


Davegt74
 

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Hmmm, not a bad idea Dave. I could stop at Tom's shop the next time I'm in Vermont and do a full-blown photo shoot of the car, including the undercarriage (has custom front coil-over suspension, quick-change rear with Watt's linkage and coil-overs, etc.) I mean, there's not much Opel LEFT really, but it's cool just the same. It would be neat to cover one car per month and do a 'feature article' on it. I used to write a little for a Nissan online magazine, it was a cool concept and easier than a paper magazine. I'll ask Gary if we have the room for it here when he gets back.

Speaking of photographing cars, when are you going to take some exterior shots of your racecar and Marty's (rotary GT)? Don't need any MR2 photos though.....:D

Bob
 

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Ha Ha OK no PICs of Toyotas

but how does an Opel with a DOHC 20 V Toyota motor sound Ha ha

my vote is in for an article a month

I should mention that Tom Drake's GT came the closest to a National Championship some years back

and could be knocking at the door with some of the tech advances that are coming out for the Opel CIH motor

We should write letters to the comp board to allow the use of any factory Opel head that will bolt up without modification.


except the DOHC head

(i saw some similar wording on the spec line for the Datsun 510)


Davegt74
 

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It wouldn't help to get another head, that's not the issue. We are restricted to our current valve sizes because of the bore diameter, nothing else. And we are restricted in terms of airflow not by the head, but the carburetor sizes that we are required to run. The heads I've done for GT-4 engines will outflow a stock 2.2 Opel head, but the carbs choke them down. Putting a better flowing head with the same carbs won't help anything unfortunately.

Now IF they decide to bump the Opel to GT-3 (which has been talked about), then we need to lobby for a 2300 cc limit and unlimited carburation with any head. So we could bore a 2.2 out 2 mm's to get 2297 cc's, and run a mega-valve 2.2 or 2.4 head with twin 50 or 55 Weber sidedrafts, and the roller cam setup. Then we could be competitive in that class, and comparably equipped to the Fords (2300 cc's with Esslinger head).

BTW, I just got word that Jim MacMahon DID end up winning the ITB race today at NHIS. Track was nice and dry, just like he likes it! No word yet on the results of Tom Drake and Ed Funk yet.

Bob
 

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is it harder to port a 2.2 head or a 1.9 head?
also i figured the raised port would help things out
maybe not in ultimate power but the area under the curve
and that might be where things are at anyway

also

I thought they changed the rules for GT

Something about FI on individual runners
if that's the case you could get the aux. Venturie out of the way


but it would be of little help

a friend says they notch the cyl wall to make room for larger valves

ever here anything like that

i wonder if the 0.047 limit is measured half way down the bore

oh well it would not mater much those DOHC motors have 1.1 inch valves
and the got 4 of them

Davegt74
 

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A 1.9 head is harder to port for sure, but it actually flows more air at .400" lift than the 2.2, and has higher port velocity. Plus, the 1.9 has a better flowing exhaust port that happens to be smaller than the 2.2's as well. Basically, it has more usable airflow 'under the curve', and the small imtake ports will provide better torque. Admittedly, the 2.2 head is better if the engine does not have the intake restriction, but you must also rev it higher to utilize it. True about what you said in reference to IR FI, you could run a straight 45 mm TB with no venturi, and we'd DEFINITELY see more power. We are seeing 197 hp from that engine out of a theoretical 221 hp available from the head's airflow. The induction system might free up another 8-12 hp by my guess, and a new header might get a couple more, but I think we're about maxed out at that point, unless we want to start building 'one event per engine' type of powerplants. Tom gets about two years between rebuilds, most other top National drivers will freshen the engine 2-3 times per year, so the Opel has definitely been durable.

I've already designed a custom TB setup for Tom's engine, where each 'pair' of intake runners have very closely spaced twin TB's (about .250" apart), so the line-of-sight is better to the valves. Using the commercially available Weber DCOE-based TB's requires the airflow to make too many turns, as they start wide, narrow at the entrance to the head, then go wide again at the valves. I'd like to streamline it, and also work on injector spacing and possibly twin injectors for higher rpm stuff. Apparently, the BTCC guys found that a small injector close to the valve is best for torque and response, but at higher rpm they 'stage-in' a second injector and they actually place the injector OUTSIDE the air horn, spraying into the TB for more top end power. Interesting amount of R & D going on there! I'd like to spend some time developing it for an Opel, but Tom hasn't had much time lately to even race, much less spend thousands of $$$$ on the dyno developing new ideas for his engine. We'd still have to determine the optimal runner lengths, the optimal TB spacing from the head, runner angles (without hitting the hood), design and test a new airbox (getting the correct plenum volume and airhorn spacing for proper 'reflective' tuning against the top of the plenum), etc. etc.

Unfortunately, we can't notch the Opel block for bigger valves because with the longer rods, the ring stack is pushed so far up the piston you'd compromise the top compression ring seal at TDC. Even if you notched the block, you'd still have shrouding issues. A larger valve simply flows less air in a smaller bore, but you've added mass to the valvetrain so the spring rate must go up, etc.

Bob
 

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Apparently, the BTCC guys found that a small injector close to the valve is best for torque and response, but at higher rpm they 'stage-in' a second injector and they actually place the injector OUTSIDE the air horn, spraying into the TB for more top end power.
Bob [/B]



This really isn't anything new. At lower port/intake velocities the best mixture is obtained with the injector basicly in the head. This avoids the seperation problems of 'turning wet air' and collection of the gas on the port/intake walls. At the much higher port/intake velocities the tendency to collect on the walls is all but eliminated and the increased time in the intake helps the mixture quality. And because the air in the intake is dry at the lower rpms you need not be as worried about it's velocity and your intake can now have a larger cross section, helping high rpm breathing. Beyond this, engines with a large dynamic range need a staged injector system anyway due to closing times of the injectors. This is somewhat over simplified but I think you get the idea.

This is the difference between an injection system done right and just bolting on DCOE replacment throttle bodies and finding out you gained little over a properly tuned carb.....except a lighter wallet:)

Bob, do you need butterflies in GT4? If not, take a look at the new Lumenition throttle bodies$$$. They look pretty sweet!!!

-Travis
 

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Travis said:

Bob, do you need butterflies in GT4? If not, take a look at the new Lumenition throttle bodies$$$. They look pretty sweet!!!

-Travis
I'm honestly not too sure, but you can bet I'll check the GCR tonight! The only problem with the Lumenition stuff is availability of spares, and customer support. About ten years ago I tried to become a distributor for them, but they wouldn't sell to me because I didn't own a rolling road (chassis dyno for you non-Brits out there!). I'll contact Demon Tweeks and see if they stock them yet. Thanks.
Oh, and check out the Jenvey (they're a UK company too) throttle bodies, they're sweet and VERY reasonably priced. Lots of options too.

Bob
 

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Wow how cool is that

I like the Toyota 20v quad TB's

i traded some Toda adj. cam gears for them

but they could be had for around $200

the Australians say they are good for 900 CFM (i doubt that) but they look dam good

also each one has its own spring so spacing is no problem

they are taper bore

this leads me to another idea or question

if i used a stock Opel FI manifold

i could go one of two ways. cut the manifold just past the injector hold down things

and run them like DCOE's
or actually have a manifold that curves and run Individual TB's like a down draft setup

of course the best bet would be to cut the runners off weld on a flange and could try both

sidedraft style or down draft

it took a while but i finally figured out how to make a cool air box

i know its easy for you guys but i hand never seen how they make them just saw the finished product

to bad QED took the info off there web site
they had some real good info
and i think Jenvey got there info from QED



Davegt74
 
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