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Thanks, Now I see. Thats going to take some trick machining to keep enough margin to maintain valve strength. Maybe oversize valves cut down? I'll have to do some measuring and thinking....
 

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Thanks, Now I see. Thats going to take some trick machining to keep enough margin to maintain valve strength. Maybe oversize valves cut down? I'll have to do some measuring and thinking....
yes the stock valves have too thin a margin to do a chamber side cut.. an oversize valve cut down in diameter would work.. you leave the chamber side cut sharp as that reduces reverse flow back past the intake valve... the exhaust valve likes as wide a margin as possible as far as flow is concerned, only problem that makes for a heavy valve so it is a trade off..i have never done it and i would bet it cause exhaust valve failure on a turbo but i have seen exhaust valves with a "ditch" cut into the back of the valve to reduce reversion,,,basically making a dam against reverse flow...
 

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I have tried degreeing of cams (slotted sprockets), about 6-8° less overlap and 5° higher spark advance, but was not content with the results, the EGT was still far...
Did you adjust both of the cams symmetrically?
Did you notice any changes, less low en torq, more high end torq, less fuel need, faster spooling etc?
 

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Autobanmod
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Discussion Starter · #64 ·
that was quite a while ago, yes I did them symmetrically, EGT went down just 50°C, the typical engine characteristic remained more or less unchanged, I did't dyno it
 

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Ok, I've been driving the bike and have some results. Although they won't be detailed enough for most of you. I put it on a dyno the other day and was disappointed. Not the bikes fault. It made 120 hp at 60% throttle, but 100% throttle fluttered out and wouldn't run over 7K rpm. All the tuners around here have never seen a turbo, so I was just getting a read out. I checked the Twin Scan when I got home and saw the fuel going lean at 7K 100% throttle. I fixed that in the PCIII USB. I took it out to a deserted highway and tried to do a 100% throttle pull. The first few tries failed because I was hitting the rev limiter before I could reach 50% throttle. I tried a full throttle roll on from 25 mph in 4th gear. I shut down at 100 mph because it was so scary. Later I saw I was at 8K and only 80% throttle. The acceleration is ferocious (maybe I'm not used to riding it after working on it so long). I ran first gear up to about 50 mph and when I hit second it felt like the rear tire broke loose a little bit. I know it's all subjective and seat of the pants,but I'll be back on the dyno in a few days
 

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You may be exceeding the limit of either the fuel pump, injectors or both. I'm running Destroyer injectors and a Mustang fuel pump with a Tmax. It appears from the Forum to be the weak link on Turbo systems.
 

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that was quite a while ago, yes I did them symmetrically, EGT went down just 50°C, the typical engine characteristic remained more or less unchanged, I did't dyno it
okay, then it is waste of time and not worth of risk to loose a slotted gear.

btw. mr silversurfer, mine did smoke tyre easily w/o any clutch teasing with 4th (30T) when boost came, ....but just for a while while -then pang:eek:fftopic:
 

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okay, then it is waste of time and not worth of risk to loose a slotted gear.

btw. mr silversurfer, mine did smoke tyre easily w/o any clutch teasing with 4th (30T) when boost came, ....but just for a while while -then pang:eek:fftopic:
with the slotted sprocket you can degree the cams in and then pull them out and pull out one bolt and machine a small aluminum spacer to fit in the slot to keep the sprocket from slipping and reinstall the bolt... we used to do this but it was a lot of work... the last time i degreed the cams is didn`t and have had no problem with slippage but it does cause me a little worry every time the motor goes to high rpm`s...
 

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Any new knowledge of timing of 1130cc stock cams in turbo use?
I have new sprockets in my "new" motor and I'm going to slot them to reduse overlap and dynamics compression.
New experiences and suggestions would be very welcome.
 

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Autobanmod
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Discussion Starter · #71 ·
Short before he sadly passed away, Tim kindly pm'ed me following insight:
sideways67 said:
This is my opinion on turbo cams with the v rod. Use stock intake 1130 or stock 1250 cams with 114 lobe centers, use the same intake cams on the exhaust side at 112 0r 114 centerlines.Using the intake will require you use the exhaust gear and slot, also of course removable of the compression releases. While this may not be the absolute ultimate in cam selection its damn close. I believe you could chase different profiles for the rest of your life and not improve to much over this setup I could be wrong just MO Tim
PS I would like to share more with the forum but won't until we set the record.
 

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Thanks to TIM.... and Jan when you shared this.

I think I will try intake cams in both of sides. Lobe centers 110-112deg.
Have You tried this specs Jan?

Is there a stronger starter in 1250?
 

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Did a little drawing job to understand better and to compaire to other turbo applications.

Stock




Double intake cams, centre lobes intake 112 deg and exhaust 110 deg
 

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Killer Service Inc.
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Same sproket for both cams...

I had a vibration...but the bike needed to be tuned.
 

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Does somebody have specifications of 1250 stock intake cam?
duration (1mm lift)?
lift?
 

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Autobanmod
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Discussion Starter · #76 ·
I tested 1130cc cams (4xintake) without degreeing. Didn't dyno it, but it felt like more torque in low and mid range (front wheel seemed to lift more easily) and less pronounced "stampede" from 5k upwards.
 

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I tested 1130cc cams (4xintake) without degreeing. Didn't dyno it, but it felt like more torque in low and mid range (front wheel seemed to lift more easily) and less pronounced "stampede" from 5k upwards.
Jan, you say you installed the cams without degreeing. Did you use stock sprockets on both intake and exhaust? Sounds interesting!
 

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Degreeing your cam is going to move your powerband like you said. Adjusting ignition timingand fueling will get you the most out of that cam.
 

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Autobanmod
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Discussion Starter · #80 ·
I've started measuring my setup with 4xstock intake cams
Findings front cylinder:
@1mm lift Exhaust opening 58° before BDC and closes exactly at TDC, lobe center is around 119°
@1mm lift Intake opening 16° before TDC and closes at 42° after BDC, lobe center is around 103°

duration based on 1mm lift: 238°

Tomorrow the rear cylinder...

This was done by turning the engine the same way around as it operates, the pin of the gauge touching the tappet

This are quite different values compared to what the guys from Schrick predicted for 4x intake:
Their figures were:
Exhaust lobe center 112°, @1mm lift opens at -236° and closes at 12°
Intake lobe center 106°, @ 1mm lift opens at -18° and closes at 230°

strange...
 
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