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2 SUs become 3 OER 45s


fhptom

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Well I finally got my wish and got a set of OER 45 triple carbs.

They bolted right up with no problems and car started on first try.

Idles and revs great.

 

Oh the sound is SWEET!!!!!

 

Drove it down to the end of the street and like everyone says

"it sure feels faster"....

 

As soon as I get back from Vegas trip I will take it back to the DYNO and get the real facts.

Now everyone will know if triples really are worth the cost.

 

One question though, since I lost vacuum assist for brakes on intake manifold what do I do with it? Cap it off and push harder or is there another answer.

 

Tom

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Well I found the port on the intake manifold for brake booster. It was just blocked off with a plug.

 

Next question for other triple carbers, especially those that track thier cars.

 

My carbs came with 3 K&N filters also but I am thinking about not using them and just getting some caps from Pegasus Racing.

 

Will that tend to allow too much air into carbs that I might have to recalibrate?

 

Knowing that I now have to buy 6 of everything if I need to retune.

 

Tom

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Not sure what you mean by "caps" but if you're talking about the sock type filters I'd say stick with the K&N's. Several years ago I saw a test and the socks were the worst flowing filter of all of them. Best in my opinion is the ITG. Largest element and doesn't have a cap on the end like the K&N so air can enter from any angle.

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The caps are just a plastic/rubber ring with a fine wire mesh/screen to stop any debri from entering air horns.

 

Picture the lid off a jelly jar with the middle material gone replaced by wire screen.

 

I was using the ITG foam filters on my SUs. I really liked them but the foam barely lasted 3 years on my car before it started to crumble.

 

Most of the cars I see at the track running triples or any type of velocity stack(old Ca-Am cars) do not cover the air horns.

 

I thought I could just sell/ebay those nice K&N filters to recoup some of the cost of the OERs.

 

Tom

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The screens have the same problem as the socks; they're too close to the airhorn. Supposed to not flow so hot from what I've read.

 

No filter is obviously best, but then you're exposing your engine to whatever gets sucked in there. I had a friend who ran his L16 with no air horns for a while and he had the only L series I've ever seen with a really bad ring ridge when he rebuilt it a year or so later.

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  • 1 month later...

Well I finally got to the dyno to see if going to triples increased HP.

 

Previous Setup - L28 block .040 , N42 w/Stage II cam, 6-2 header

dual SUs.

 

165.8 rwhp 163.4 lb-ft @ 5500 rpm

 

New 45mm OER carbs with short runner intake, airhorns and K&N filters

 

184.5 rwhp 177.2 lb-ft @ 6200 rpm.

 

A/F ratio stayed close to 13.5 for most of pull.

 

I was quite happy with results and this might finally let some people see what can be gained by going to triples. There is probably a little more still in the motor due to the fact I did not go to about 6800rpm plus the carbs have not been tuned to my car.

 

Just a little more info then the butt dyno response you get from a lot of people.

 

Tom

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20 whp with no tuning is not bad. I'd suggest a bigger cam, and you need to rev it higher to use the new induction to its full potential. You should have a lot more power potential there. What's your ignition like? There are quite a few hp tied up in the timing as well.

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Jon, I am running MSD 6A with stock distributor.

 

I have wanted to change out cams but cannot decide on how wild to go.

I actually have the MSA Stage III .460 lift with 270/280 duration..

What specs do you think would be good for my engine and track use car only.

 

Yes I know that I baby my car as far as rpms are concerned. My buddy tells me that everytime we do a track event together and I am shifting way too low in rpm range. But I look at it as just fun and this motor has lasted 6 yrs of track events with comp still at 210 across all 6 cylinders.

 

Tom

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I don't know much at all about the 260 distributor. Is it points or EI? What you would like from a distributor is somewhere between 15 and 20 degrees advance at idle and 32-38 degrees when it is all in, which should be somewhere around 2500 rpm. You should disable the vacuum advance and lock that part of the distributor solid so that it can't allow the timing to change. If you were wanting to change, the 280ZX distributor has 17 or 18 degrees of advance, so the curve is right, and it is all in at 2500 rpm. The vacuum advance on the ZX unit SUCKS and they're almost always broken when you pull them from a parts car. Not sure if the 260Z is as fragile, but it would be worth looking into. Of course there are a number of good DIS options now and you can do more with the curve on those.

 

That stage III cam is really way too small to take advantage of those carbs. I'm using something roughly equivalent to their stage IV and I think that is still too small. I'd look for something with lift in the .500 - .550 range and duration in the 300 to 310 range. The lobes on a Z cam are asymmetrical and so its tough to say how a cam will function just by the numbers, but that should get you in the ballpark. This recommendation would still be marginally streetable. If you read the L6 sticky threads you'll see that there are people running Sunbelt cams that only use one valvespring and top out at about 7500 rpm, that seems like a really cool setup to me, also BRAAP has been using a Rebello cam which should fit the bill nicely. There are much bigger cams available, but you still need some low end torque for autox which is why I wouldn't suggest something REALLY big like .620 lift 320 duration...

 

Yes I know that I baby my car as far as rpms are concerned. My buddy tells me that everytime we do a track event together and I am shifting way too low in rpm range. But I look at it as just fun and this motor has lasted 6 yrs of track events with comp still at 210 across all 6 cylinders.

Believe me I understand this. Budget is always my main concern, and if you blow up a motor it can get expensive. But nothing could be more fun than getting out of it what is there to be gotten... :D

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Here is a picture of my box on a set of SK Racing carbs. I am setting it up for forced induction, via supercharger. OER are a later model of the SKs from what I understand. There is added HP to be had by getting cold air induction. Cowl induction would be another way.

 

Carb_Box_1.JPG

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Well I finally got to the dyno to see if going to triples increased HP.

 

Previous Setup - L28 block .040 , N42 w/Stage II cam, 6-2 header

dual SUs.

 

165.8 rwhp 163.4 lb-ft @ 5500 rpm

 

New 45mm OER carbs with short runner intake, airhorns and K&N filters

 

184.5 rwhp 177.2 lb-ft @ 6200 rpm.

 

A/F ratio stayed close to 13.5 for most of pull.

 

I was quite happy with results and this might finally let some people see what can be gained by going to triples. There is probably a little more still in the motor due to the fact I did not go to about 6800rpm plus the carbs have not been tuned to my car.

 

Just a little more info then the butt dyno response you get from a lot of people.

 

Tom

 

What is your CR, 10:1? I was able to muster 180WHP from a 10:1 L28 with the same cam and fuel injection (port matched 280ZX intake manifold).

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Well I finally got to the dyno to see if going to triples increased HP.

 

Previous Setup - L28 block .040 , N42 w/Stage II cam, 6-2 header

dual SUs.

 

165.8 rwhp 163.4 lb-ft @ 5500 rpm

 

New 45mm OER carbs with short runner intake, airhorns and K&N filters

 

184.5 rwhp 177.2 lb-ft @ 6200 rpm.

 

Um....those numbers don't seem to match up according to my math. If you are making 177.2ftlbs at 6.2k, you should be making just under 210whp at the same rpm. Conversely, if you're making 184whp at 6200, you should only be making 156ftlbs at the same rpm.

 

Unless being on summer vacation since yesterday is messing with my head.

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  • 4 weeks later...

Hi Tom...

 

The link below is a must read on selecting cams. I hope it helps you decide

to release the HP monster lurking in your engine :flamedevi

 

http://www.datsport.com/Racer_Brown_Menu.html

 

Jon, I am running MSD 6A with stock distributor.

 

I have wanted to change out cams but cannot decide on how wild to go.

I actually have the MSA Stage III .460 lift with 270/280 duration..

What specs do you think would be good for my engine and track use car only.

 

Yes I know that I baby my car as far as rpms are concerned. My buddy tells me that everytime we do a track event together and I am shifting way too low in rpm range. But I look at it as just fun and this motor has lasted 6 yrs of track events with comp still at 210 across all 6 cylinders.

 

Tom

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