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Thread: Cyl head port design

  1. #1
    4cyl H2
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    Ive got a gs 1166 motor with a rajay ff 40 turbo, & zenith carb 38 mm, 1150 cams, 108 I 112 ex)I dont think it has the power it ought to, 13 lbs of boost puts it about even with a stock 001 busa, the cyl head has a mild street port with stock valves, the bike doesnt do anything wrong (no detonation, flat spots,& revs ok, driveabilitys not to bad for a zenith),intake & exhaust have been done, the design works well on my n.a. motors, wondering if stock head would work better with turbo,also have a head , looks like star ported intake & stock on ex, already done the ign,& carb tuning doesnt help much, any thoughts


    Bart how about your thoughts


    thanks

  2. #2
    rajay
    Guest
    That ff40 will with that Zenith WILL show 240+ at the back wheel. 285 at the crank.

  3. #3
    Junior Member Marc Powe's Avatar
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    4cyl H2,


    When you say it does not have the power it ought too, where do you feel it's lacking Low end Mid range or Top endWeatheror not the stock head would be better would depend on theanswers to the aforementioned. The head with the smaller ports may work better for the street and with low boost but I really don't think the mild ported head that you are currently using is really hurting it. A different turbo would spool up better than that rajay however it would involve a few modifications (T3, T-25, T-28 or T3/T4 hybrid with the right wheels and housings for low boost levels). Maybe a change in cam timing. Maybe add a water injection kit so that you can run a few more pounds of boost on the street or so that you can increase your static compression a little. Or, maybe changing that carb will do the trick.


    Just thought I would throw a few things out there...............maybe it will give you some ideas.


    (Your combination is very capable of producing the horsepower levels that were mentioned in the previous post however at much higher boost levels.)


    MarcEdited by: Marc Powe
    NuSouth Drag Racing Leauge, LLC
    www.ndrl.us

  4. #4
    4cyl H2
    Guest


    mid range & top end, normal 1/4 mile speed is about 140, @ 15 to 17 lbs of boost, 145 mph best ever, I was running forged 72mm pistons befor the 75s, didnt seem to make much difference, (mtc turbos, 0 deck) bike is 500lbs, im 208, would really like to see 150 mph at same boost levels, I have anE compressor wheel & housing, wondering if it would help, boost builds quick enough, just like to see more push on boost, been told an hsr42 would help,& i can see better driveability, but dont see it helping power, bike is an 81 gs1100,plus 6in arm & mr turbo tailsection,no bars, streetbike, any thoughts on cams, i thought the 1150s would be good (even know some guys use them in top gas)



  5. #5
    Junior Member Marc Powe's Avatar
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    A better carb will increase hp. The rest of your set up sounds good. With the small motor I don't think the E flow is necessary. Plus, you still can get more boost out of what you have. Keep in mind, an 1166cc motor is still considered a small motor. Especially in this day and time. I had a street/strip KZ 1015cc turbo with a 38mmKeihn back in 1990. The bike was basically stock except for the aftermarket pistons. Stock head, stock cams, stock KZ tranny that was back cut. The bike was raked with a stock swing arm that was modified with 3 additonal inches. I had a 3.5 inch rim with a 7 inch old style slick and bars. The bike went 6.0's in the 1/8 at 121 mph on 16 to 17 pounds of boost. I later went to a 1075cc motor and a 4.5 inch rim and a 7 inch slick. The bike went 5.80's. After this I did some major changes. I went to a car tire, GPZ tranny semi auto, 1135cc motor, S&S carb(I also used a 40mm Keihn that worked well), ported head, cams etc. It started out being a Super Comp bike and It was alot faster. I later changed from the Rajay to a Garrett. I was still learning how to tune the little motor and never really got it dialed in. However, It wound up running a string of 5.30's in the 1/8 at 133 mph. I also went a 5.28 e.t. at only 124 mph because the tranny wasacting up and it would not shift. The bike went screaming through in 2nd gear..............again producing a 5.28 e.t. (bike and rider 685 lbs).


    So, the little motors will run but you can't be to shy on the boost if you want to haul ass and run with the big boys. I would start with the carb first. After that, turn the wick up............20 psi!!! You may want to look into a two stage wastegate to help regulate the power. I've also experimented with 9 and 10:1 static compression with the little motors and they wake up. I was using race fuel however I do know of some persons that have used water injection with 9.5:1 ++++ static compressonon the street without detonation. I believe Ian King (Top Fuel Racer) had a similiar set-up.


    I hope I was able to help!!!Edited by: Marc Powe
    NuSouth Drag Racing Leauge, LLC
    www.ndrl.us

  6. #6
    4cyl H2
    Guest


    Marc thanks for the info, you think, an hsr42 would help enough to justify the cost I figured the zenith had plenty of air & fuel flow to do the job.


    Would I see much difference with the E wheel, I thought it would help build boost quicker, but ive been told it will slow down build time


    1 other thing i thought to check is the gauge, its a glycerin, filled gauge, but with the engine off it reads 1-2 lbs, is there an easy way for me to check it

  7. #7
    Junior Member Marc Powe's Avatar
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    Yes,


    I think a carb upgrade is worth the cost. Check around, you may find a good deal on a used set up. I think I saw one on the classified section. As far as the E-flow is concerned you would probably build boost even slower. The smaller A/R ratio housings will build boost quicker. Funnybikes have gone into the 6 second zone with the turbo that you have. Later on down the road you should look into another turbo for real efficiency (like the ones I mentioned earlier). I've helped several racers to convert their systems over to a Garrett or Garrett style turbo like we sell and they will tell you that you hear and feel the difference. You can create different combo's with these turbo's. You can actually tune with them. For now, I'd start with the Carb.


    Vibration will kill those gauges. See what brand it is and try one of your local industrial gauge shops for a replacement. I use the McDaniel Controlls gauge. Their is a place near my home that sales them.McDaniel use to sell them directly but now you have to buy them from a distributor. Look up McDaniel Controllson thenet and maybe they willlist a distributor near you. Make sure that you don't have it mounted to rigid.


    One more thing, make sure you don't have the carb that you have to rich. That's one of the things that I found out that I was doing with my 1135cc Top Gas bike. I was too rich and it just killed my low end torque. I found this out when I took the motor down. My pistons were way to pretty for 30 psi of boost. With a little cleaning in the parts washer they looked brand new. I found a few guys running 1425cc motors that were using smaller jets than I had. Again, the little motor will get down however they are not as forgiving if the tune up is a little off. Keep your tune up a little rich on the street and then drop it a jet size when you want run someone on the track. By the way are you gravity feeding it or do you have a pump
    NuSouth Drag Racing Leauge, LLC
    www.ndrl.us

  8. #8
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    Marc , I'm curious about your "rich" condition , are you saying you were washing down the pistons rather than carbonizing as I would expect to see in a rich situation

  9. #9
    Junior Member Marc Powe's Avatar
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    I guess you can call it that. You would think 30 plus pounds of boost with 9.5:1 static compression and 34 to 35 degrees of timing would have given those pistons a little hue. I sold the block and pistons to Paul Stuart (7 second T/G Nos Kaw) of Stuart Racing out of G'ville. He put them in a bracket bike. He frequents these forums and he could not believe what they looked like after I told him what they came out of. I was also using B8ESplugs with a Dyna 4000 ignition. Being rich did not seem to hurt the mid range and top end. I ran 5.30 e.t.'s with only a 1.31 short time. My mph would range from 130 to 133. It has gone 135 mph.A good guy by the name of Tommy Hines who runs a 1425cc Kaw with a 3 speed told me I was a little rich. He was running a smaller main jet than I was in the 1/8. At the time, I had already had many laps on my GPZ tranny from a previous lower compression 1135cc motor and I was hoping it was going to hold up long enough for me to dial the motor in. As I mentioned earlier I ran a 5.28 @ 124mph because it would not shift into third. I put some new forks in it and it was ok. I decided that I was going to lean it out at the next race that I planned on attending. On the first pass the tranny went to binding up and walla...........it broke. So, I decided to go ahead anddo alot of other changes instead of just fixing the tranny and I never did get to see exactly what that motor could have done. It did make 256 hp to the rear wheel and at the time it was still not running very clean during the dyno runs. I didn't make but two pulls on the dyno because those things spook me (smile). I learned some valuable things with that motor and hopefully it will keep me in the saftey zone with my new 1394cc turbo/nos motor with a 3 speed and new top end set up.


    I am going to build another small motor for Top Gas and as a back up so that I can race and have some fun if the big motor needs fixin.....smile! The next time I know exactly what to do and I even have a better tune up for it this time.
    NuSouth Drag Racing Leauge, LLC
    www.ndrl.us

  10. #10
    4cyl H2
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    Ive read up some on turbos& understand about the ex AR ratios,but I didnt realize how much effect a larger compressor wheel could have on spool up time, figured the shaft might spin up slower, but push more air on each turn, im running a pump & reg set on 2.5 lbs

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