ben wight

[4BIDIN]

Gday ben
Ive worked on cars with straight manifolds there are a couple in brisbane also sbend and idf carb set ups.
the tx master is the way to fit a twincam with twin webbers most dont run a booster at all it makes the pedal hard but thay still stoped.
As far as the diffrence in out right power it all comes down to trying to reach 100% veo. to do this a straight manifold is good but you also need big comp / ign and air speed dose need some gravity to makeup speed
a big down fall in the straight manifolds.
I think for all the effert the gain is small.
look at my car it has an IDF webbers set up and run 12.65.
anther guy called mark runs a 600 holley and runs 11.77 both on nitous but what the hell its all hp.
The money you save one the brake conv you to could be
a bottle feed 4 .
hope this helps??

[Ben Wight]

Thanks for the info, but I would prefer to keep my booster, do you know where they got the straight runner manifolds from?

I am considering blowing through a pair of 40mm dellortos, and was going to make my own manifold, when I thought it might be just as easy to buy an off the shelf Lynx. I am not decided as yet, as I am not sure of the benefit of blowing through quad thottles instead of a double barrel carb on the factory but heaviliy ported manifold.

The main reason I would like to try the twin sidedraughts is for better mixture distribution, as the factory manifold leans out cylinders 1 and 4 due to the longer and curved runners, relative to 2 and 3. And I would prefer to go sidedraughts as I have a few lying around.

I am still researching this, and I may just keep my current setup which is a single downdraught 38/38 DGMS. Many people have tried to tell me that it wont be of benefit to fit twins over a single carb as you are forcing air in from a turbocharger anyway. All of this info comes from people who have never conducted any form of research, and basically just imagining the process of blowing in air, and thinking if the pressure in the airbox is X, it doenst matter how big the carb is, the pressure in the manifold is going to be X at wide open throttle.

Well this certainly isn't true, or else a bigger carb in a blowthrough application would have no effect, and a bigger carb certainly does have an effect. I know that any reduction in inlet restriction is a good thing. Comparing 4x40mm butterflies to 2x38mm butterflies gives an indication of the extra airflow, so it certainly cant hurt, I just dont know how beneficial it will be yet.

A 2 litre on 22psi is rougly equivalent to 5 litres of capacity, and I certainly wouldn't want to run a 5 litre engine on a single 38/38 DGMS.

[4BIDIN]

lynx make the manifold for about $200.00.
As for blow through turbos one of my friends had a 1.8 draw through with a to4 and 45mm weber ran 11.65 @ 117mph .
Then put on a set of 45mm webers in a blow through set up and ran 11.40 @ 119mph .
the big bonius was off boost driveablity improvment was LARGE tuning was mind blowing many many many late nights .
but will make GOOD power right through rev range .

[Mark]

The only downside to the overall story is that if you want to run twin 45mm sidedraughts, the motor has to be worked enough to run carbies that big off boost. Ive got a friend with a t04 on his gem and it was running a 465 holley suckthrough and it drove like a pig off boost cos it was simply too big for the motor, but it hauled on boost. We down changed the carby to a 2bbl 350 holley and it pick up drivability shitloads and any loss in outright power was negligable, which indicates the restriction on making more power was something other than the carby.
Do you really need twins on your setup?

[Ben Wight]

I dont think I need twin carbs, but I do think I need a better manifold. Twins then is the only way to run a better manifold. I will be using Dellorto 40mm DHLA with 32mm chokes, these are factory fittment to a 2 litre alfa, so they definitely wont be overcarburetting the engine. I am running a 3 litre carby right now, and am loving the responsiveness of it. I think 45's would be perfect, but I only have one 45 DCOE, so will be mucking around with the dellortos for a while. Might have to go bigger chokes though.

Lynx dont make the sidedraught manifolds anymore, so I am trying to find a SH one. If you guys know of anyone, let me know. I may have to make one after all, the only problem being the aluminium mandrel bends I can get might not be tight enough to make the 's' shape, and making a thermostat housing is a bit of a pain.

[JFK]

if i new were u were i could get u one but im to lazy to send it anywere and im in penrith and there of twin 40 dellortos for the gemi from mine
i had twin 40s and sold em to guy for his alfa
and kept the manifold

[Ben Wight]

I am interested in the manifold you still have. Is it a lynx twin sidedraught, or another brand? I am in Ballarat, VIC. You could COD it to me. How much do you want for it?

Cheers!
Ben Wight