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Need to cut 100hp

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How could I cut non visible 100hp ?

The car needs to pass a dynosession done by the government aprooved dynoshop. (180 SAE HP max.)

 

Are there any inlays/inserts available to choke down the ported inlet channel (cylinder head)?

Choke down the tripples?

Block the throttle to 50% max (to easy to see)

 

Do you have any ideas?

 

Thanks

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Well this is a fun exercise.

 

What are you running? Whatever it is is 280hp apparently. If it is a V8 you could cut spark and fuel to 1 bank. If it is a turbo you can just keep the waste gate fully open. If it is a high compression NA L6, I'm not sure what you could do other then make it run pretty bad via restrictive exhaust and intake.

 

It is the reverse of making a car run well. So you have air, fuel, spark, compression, exhaust you just have to limit those without causing too much damage. I imagine limiting air would be a relatively easy one.

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Ya, limit airflow. Trying to cut 100hp via timing, fuel, etc. is going to be difficult and potentially risky. You could waterjet cut some thin sheetmetal restrictors to go between the carbs and the manifold, or between the intake and the head. This will probably be the least obvious as you're not going to get a big change in engine sound like you would with timing or cutting spark to cylinders. This will take some trial and error to get exactly what you want.

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Change the throttle opening for the first and third carbs so they don't open fully.  Inspectors are most likely to only check the center carb because its easier to view. Reduce timing.  Loosen the valve adjustment.  Change the cam timing (retard it). Richen the carbs to 10 to 1 under load.  Add an exhaust restriction.

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I concur with intake and exhaust restrictions.  Childrens motorcycles are restricted in exactly the same way.  As previously suggested build restriction plates for both the intake and exhaust manifolds and then tune your carbs to match the new flow.  This is going to be tricky to determine if you are under 180hp without a dyno though.  If this is a regular problem i would consider using another set of stock carbs tuned to your restriction plates so you could bolt on a known system in the future.  An RPM limiter set real low might help as well.  Good luck

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Thank you all for your thoughts

Exhaust / intake noise  is 5 db to high as well

I will start with smaller jets, less Timing advance set, set the throttle opening at 90% max, loosen the valves by 0.05mm, set the rev limiter to 6800, install an Airbox and restrict the exhaust.

 

Then I will go on a Dyno to see where I am.

Next step restrict the carbs. I have to find a non visible way (internal before the flange or make my own casket)

 

This is really cool from all of you

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Madkaw I will update my build tread (me lazy bum with the build tread) and post it here when done.

This is the build tread with some more pics

http://forums.hybridz.org/topic/102748-build-after-24-years/page-4?p=1167828

 

 

I finished the restoration and this was my first show up at the MFC/TUV/state inspection after 28 years without registration.

The only difference is in Switzerland they are quite picky.

 

For example I have to go from stage 4 rear disc upgrade back to drum break or have it testet by an official government test center (costs 1500$) because I don't get a form signed and aprooved

by nissan.

The inspector didn't like the triples eather (not factory original) so he wants to know how much hp the engine makes with them.

If it makes to much i have to do the same kind of test like for the brakes but depending on how much more it makes. (20% more is alowed)

between 20% and 40% the test costs are around 2.5K$ (If I would keep the rear disc it would be 1500$ less) above 50% the cost would be in the range of 5K$ to 15K$.

 

theoretically I have to do the test just once and then it would be written in the vehicle registration paper.... "triple Carb setup with 180bhp" or something like that.

Edited by munters

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Put a stock Camshaft in it.  Easier than Intake and Exhaust restrictors and nothing to be found. Take some ignition timing out of it ( 28 -30 degrees total Mechanical ).  Set rev limiter to 6,000 RPM or less.

 

Camshaft change will drop your exhasut DB levels as well . An Airbox will take care of Intake DB levels.

Edited by Chickenman

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Holy crap that sucks man. You can make a gasket that restricts your intake manifold down to half size, that may make a bit of torque but it sure as hell will choke up top. May as well set the limiter absurdly low like 4500 or something, it's not like they'll ask you to raise it. A big exhaust restriction will help a lot.

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No second engine to swap for dyno testing huh? That's how they did it in Japan.

 

And Switzerland is not in the EU so no cruising to a "friendly" TUV station to get your certification then bringing it in later...

 

Really, with the expenses involved, the engineering is sound regarding brakes... Why not get the brakes tested and let that determine your horsepower? If it's higher than you have there's room to grow! 

 

Expensive, but in the long run having the brakes to stop the horsepower isn't the worst thing in the world... :lol:

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I would imagine the intake restriction and lower rev limit would take care of the excessive noise and horsepower (I can't believe there is such a thing).  If it were me I would build it into the carb spacer, you can build them with simple tools and they swap easily.  Full disclosure- the extent of my smog knowledge was acquired when my tech told me to pull my brake booster vac line in my 86 corolla to clean it up.  It didn't work, I moved and haven't had a smog fit since.  This all sounds incredibly stifling to me... best of luck!

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No second engine to swap for dyno testing huh? That's how they did it in Japan.

 

And Switzerland is not in the EU so no cruising to a "friendly" TUV station to get your certification then bringing it in later...

 

Really, with the expenses involved, the engineering is sound regarding brakes... Why not get the brakes tested and let that determine your horsepower? If it's higher than you have there's room to grow! 

 

Expensive, but in the long run having the brakes to stop the horsepower isn't the worst thing in the world... :lol:

I do have the numbers matching engine in pcs. and another one in the shed for 30 years maybe this one runs ...:-)

Above the 50% more HP they would have to test the body deforming coeficient what ever this means and involves. but for shure costly. I just try to not go this route.

 

Roger

Those guys are quite often petty minded.

3 inspectors came to see the car and found it is well restored and so on.... but my inspector did not have any reaction. Just rules and figures. Luck and bad luck is always part of our life.

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Yes It could and I have 2 sets of round tops but then it would not be aprooved this way. (Police could always stop me and have it retested.)

I love the triples.

Actually I fall back to my teenage age when I drive it now after nearly 3 decades of having it disasmbled in the Garage.

I love it even more to drive then the V12 Espada (It runs also better not just the sound)

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one thing you could do is change the wires on three of the cylinders to wires that won't connect.  this way, you get an immediate 50% cut in hp.  I'd pick every other cylinder in the firing order to make it somewhat even. not great fort he engine, but...  faster and less complicated.

 

you could retard the timing a lot if you have a distributor, but that might make your exhaust louder. also not great.

 

you could put a very restrictive air filter(s).  that might help.  something very small, or somehow blocked off.... unless they can force you to test without filters..

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man I'm sorry man that sucks about hp limitations in Switzerland I thought that was very relaxed compared to other country's. ? I'm thankful I live in Texas and a great out by the country county where anything over 25 is exempt they just make sure I have seat belts and running lights. Don't even pop the hood.

Edited by Austing

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Ok finally I passed.

I did change the Jets, retarded the Ignition and especially put a Air Box with a hose connected to the smaller radiator support hole (just 2")

The mix of that brought me to 170hp and the rest I blocked the max throttle (underneat a piece of carpet nicely hidden)

 

Attached is the final Dyno Value up to 4680 rpm because it stayed there up to 7000.

Original was 120 DIN Hp and they accepted the 140 HP (+20% max. is allowed).

 

post-23044-0-07398700-1464873543_thumb.jpg

 

The Brakes I changed as well back to Drum.

The noise was also a good thing, because the measurements are taken at 80% of the max HP RPM value (in my case 80% of 4020rpm = 3216rpm) I passed at 74dB (max 74).

 

 

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