[Joe Van Wagnen]

I am starting to look for Irmscher dual side draft manifolds for my gt.... i guy has a set of shorties 80mm with thermostat housing and he is asking $250..... what is a good price??

Thanks

Joe Van Wagnen

 

[RallyBob]

Another point: The short Irmscher manifolds flow decently, and they make installation of sidedrafts in a GT a lot easier. However, the nature of a short-runner manifold is increased top end power with a loss of bottom end power. I've done back-to-back comparisons with Cannon (long intakes) and the short Irmschers, and the difference was dramatic. The long runner intakes had better torque than a single carb, better mid-range, and a bit better top end, while the Irmschers were slower than a single carb from 0-30 mph and from 0-60 mph were only 2/10's faster. They only really shone when testing 0-100 and top speed, that was dramatic. On my test 2.0 litre engine...... with short Irmscher intakes, 40 DCOES with 30 chokes, the top speed rose 17 mph compared to a ported (not welded) stock intake and a 38 DGAS.

Bob

 

[ConreroGT]

price

$250 is a fair price. I paid $500 for the Imscher manifolds and 2 DCOE 40's. I later sold the manifolds because they wouldn't fit right on the 2.2 head. I sold them for $250.

-kyle

 

[ConreroGT]

Speaking of thermostats

Speaking of thermostats, anyone happen to have a used/spare thermostat adapter plate that "lifts and seperates" the thrmostat housing away from carbs? For a 2.2 head?? Bob?? I'd like to avoid making one from scratch myself. Gil sent me the diagram but I don't have the tools. I'm aftrad to see what a shop would charge me to make one.

-kyle

 

[Gary]

Mod Note: Split the Holly 500 / 38 DGAS posts to a new thread.

 

[opeldean]

water neck for side drafts..impossible to find..but..

I saw this car on ebay last night.now its gone! 10/31/05

I believe it has a water neck/needed relocation piece for side drafts.

I would like to have it ,but someone may need i t worse than me!

car was advertized as being in oregon and being imported by a serviceman.
car was said to have a 2 liter and side drafts..which were sold separately.car has sprint..car was said to smoke,but had 500 miles on a rebuild??

 

[nobody]

Dean, It's also a GT J built by Irmsher before being imported to the states. I forget if it was wife or girlfriend that was involved and kept all the pieces from getting it all back together. It would be a sweet one to have. Oh and Dean, yes, that's where your carbs and intakes came from. I can look in feedback and find the seller if you want. I remember there being a title issue with it too.

 

[opeldean]

water neck

its was a cool gt. No need to look for owner. I happy and thankful with what i got.

maybe somebody else needs parts off this car.

 

[yellaopelgt]

Another point: The short Irmscher manifolds flow decently, and they make installation of sidedrafts in a GT a lot easier. However, the nature of a short-runner manifold is increased top end power with a loss of bottom end power. I've done back-to-back comparisons with Cannon (long intakes) and the short Irmschers, and the difference was dramatic. The long runner intakes had better torque than a single carb, better mid-range, and a bit better top end, while the Irmschers were slower than a single carb from 0-30 mph and from 0-60 mph were only 2/10's faster. They only really shone when testing 0-100 and top speed, that was dramatic. On my test 2.0 litre engine...... with short Irmscher intakes, 40 DCOES with 30 chokes, the top speed rose 17 mph compared to a ported (not welded) stock intake and a 38 DGAS.

Bob

Will the Cannon intake fit into a GT without cutting the heater core box? So if I understand this correctly, (probly not but here goes) I should be looking for a cannon intake and a set of 40 dcoe's to really get the best bang for my buck out of a 1.9l?

 

[GTJIM (R.I.P.)]

No Way Jose'

The Short Irmschers are the only ones that fit in the GT engine bay with just minor "bashing" with a ball pene hammer - except, may be the short DeBlis ones.
The Long Irmschers, Cannons and Manglotesi are longer and require the removal of the heater box. Better torque requires the sacrifice of the heater box. :ugh:

 

[soybean (R.I.P.)]

The Short Irmschers are the only ones that fit in the GT engine bay with just minor "bashing" with a ball pene hammer - except, may be the short DeBlis ones.
The Long Irmschers, Cannons and Manglotesi are longer and require the removal of the heater box. Better torque requires the sacrifice of the heater box. :ugh:

Is there anyway to recove some of the torque lost, or is it a moot point? I have the short Irmschers, twin 40 DCOES with 30 chokes, cam is (430" lift, 268 duration), solid lifters and roller rockers. Engine is stock 70 model with High Comp pistons. Mild porting will be done as per RallyBobs porting of 1.9 head post here on the board. Thanks, Jarrell

 

[nobody]

Of the known types the Magnotetsi is reported to flow the best (according to Bobs testing). but do require some heater box work. I retained the heater in mine and run a Magnoletsi with twin DCOMs. Jarrell the size of your choke tubes has a huge effect on lower end torque. For what you describe 30 chokes are a bit fat. I'd try 28s first and then maybe bore them to 29 if needed. It would be easy to have done. In a nutshell it is your air flow rate that will govern the majority of your torque curve. You are in essence speeding up the air flow with smaller chokes and it gives better responce on the low end but does limit how much total volume at high RPM you can get.

 

[GTJIM (R.I.P.)]

Torque Trix ..

The other way to enhance the lower end torque is to be a bit conservative with the exhaust pipe size in the down pipe tubes below the cast iron manifold and keep them quite long. In effect, tune the exhaust for the lower rev range as with the smaller chokes in the Webers (28 -30mm max) the motor will be less of a hi rev power maker. Say 1 1/2" to 1 5/8" max secondary tubes at least 36" long( and maybe up to 45") with the Sprint Manifold. I am going to stick with a stock or near stock camshaft too and hope it all works out with an auto trans ....... the motor should be working a lot more between 2,000 and 5,000 revs rather than 3,000 and 6.500 rpm by my reckoning.

 

[soybean (R.I.P.)]

I have a sprint for it. But what you are saying if I am understanding correctly GtJim, is re-run the collector pipes in those diameters from the sprint. Then what about the rest of the exhaust? I was planning on 2'' pipes to a magnaflow muffler then 2 1/2'' over the axle as per this thread, http://www.opelgt.com/forums/showthread.php?t=2154&page=6
and after seeing and hearing BQ97s exhaust system. This is starting to head towards the exhaust forum. Thanks, Jarrell

 

[GTJIM (R.I.P.)]

Balance ..

Yep Jarrell,
It is all about balance and tuning the twin carbs - cam - valve sizes & exhaust system to operate inthe rev ranges you use most. All very well having the torque peak up above 4,000 revs - if you don't operate the motor there when cruising! The Weber side drafts are so tunable just by changing choke size and rejetting to suit.
The exhaust set up in the thread you noted looks pretty good. After the longer pipes down from the sprint I tend to favour the 2" and 2 1/4" continuation for the torque; though I guess we need some dyno figures eventually!
PS: The tail pipe is just the other end of the 'breathing" system......

 

[yellaopelgt]

OK, so I can understand what is being said here, ( please bear with me here folks as I am a "hands on see it in front of me kinda fella!!!)It truly comes comes down to a "inhale/exhale scenario"..... in a laymans term, the easier the carb/carbs breath the same balance has to be maintained with the exhale of the exhaust. Therefore, if you open the intake/valves ect. and choke down the exhaust a tad you would get a bit of "punch" to this and there is a FINE balance of breathability. Too much out and you lose tourque, too little and you lose top end.I'm sorry guys , (I need to see this in front of my face to completly understand, so excuse my stupidity or redundance!!!! So, what is the best scenario for a streetable version that will keep up if not beat a new vehicle?? Or, is this just not do-able, is it an all balls out high priced motor w/extreme mods or can this be done without the headache of the machine shop machining your block and head down to paper and worrying abount a blowout??? I mean in reality, can you be happy with a punched out 1.9L(high comp) bored to a 2.0L (pistons)and a pair of 40's and a street cam?? Or is all this talk just a want for somthing bigger and badder??? Really, I'm in the market, have most the tools, its just a matter of gathering the parts and doing it!!! Every time I think I get this figured out,somthing or someone seems to either find a flaw in design or finds a better way to do things!The more I read, the more I get confused. thats my fault. But I dont want a 2,000$ paper weight!!!
Joe

 

[petrieopel]

I personally like to get the most horsepower out of the original engine. The Opel GT is a classic so for me building the 1.9 and putting dual webers on it was the ultimate. The thing I noticed most about installing the dual carbs was the faster throttle response so for me it was definately worth the money. The GT is a light car so any perfomance modification will be noticed in my opinion.

 

[soybean (R.I.P.)]

Joe, I believe the answer is in the, "inhale/exhale scenario",
Yes, I do believe this is doable. Besides I have seven engines etc, laying around, all in need of rebuilding. I am going to try to stay out of the machine shop as much as possible. This block probably won't be bored.
I probably will have about that much in the engine and 3 times or more, in the rest of the car. That said, for the money for the engine I was always told "build it right, turn it tight"
With a 5 speed in it, I should be able to hold my own with most cars in our class, certainly can't take a lot of the newer ones, just give them "a run for their money". After all she's thirty years + old and a lot of improvements have been made in engines. Bonus, only a few of us have an OPEL. So basically, why not do it? My thoughts, and way off topic now.
Jarrell

 

[ConreroGT]

Just an FYI in case anyone is looking for sidedraft manifolds they just showed up on eBay:

http://cgi.ebay.com/OPEL-INLET-MANI...8042278176QQcategoryZ9903QQrdZ1QQcmdZViewItem

 

[Jonzo]

For what it is worth, I just won these Irmscher shorties on German Ebay this weekend. Got them for about $150 including shipping. If they arrive in good shape then I think I'll have gotten a good deal. I was looking for a SSD set up for my GT but I guess I've been "sucked into" dual side drafts. I already have a pair of 40 Weber DCOE 2's mated to Cannon intakes siting on the shelf. So now I have a pair of Cannon intakes that are surplus to my needs. I also have a Cannon high performance cam collecting dust in its box that I got with a GT 15 years ago. The previous owner said it was a little too much for street use. I have some reservations about the dual Webers in that I prefer to emphasize the "GT" qualities of my Opel. To me that means smooth refined performance rather than raw power and exhaust roar (also I will not cut the heater box). I would appreciate hearing from others if that goal can be achieved with an Opel CIH and the dual carb set up that I have.
-Jonzo:boggled: