Hey guys, been away for quite awhile but back and looking for some info. Still have the cycle logic turbo which I had dialed, only 8 psi boost but was happy with the performance. I’m not a drag guy (careful here) nor a land speed guy. The top end of the motor is not in question. But, I never strengthen the bottom end. So, what to do? Goal still = below 400 hp and streetabile. Looking for pistons with reinforced ring lands, keep compression above 9.5.. Rook, romes.. miss you guys

My first question is why do you want to keep the compression above 9.5? RCC uses Wossner pistons and rods in their big HP builds. Steve Knecum who builds both drag and LSR motors including some Bonneville record holders which run WFO for 8 miles built my motor using CP Carrilo pistons and rods. Wossner's are 9.1 and I believe my CP's are 9.3 no matter what you choose you'll need to do rods or don't think of reaching for 400hp. Just my 2 cents...

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Hi fordtech,!I have to admit I am a bit rusty with my turbo facts. The thing to remember is this 14 will still be a daily driver. My thinking was to keep some compression for times when not in boost. And yes, rods will be put in the shopping cart as well.

Maybe a lil history, this motor has run for many years with its current configuration, I forgot how to post links but total rebuild was documented on this site. Stock lower end but many mods on the top end. It survived with 8lbs spring and with the tune using dynojet products that I worked on for 3 years. the rider said he was going about 70 and wicked the throttle and it stuck at that throttle position. He laid it over in the center lane of I35 north of Dallas and walked away. Story is the bike stayed running while on its side for sometime, how long, I don’t know. I’m guessing the motor was hurt due to lack of oil pressure.
In the rebuild phase I was able to start the motor and it sounded fine. Went thru the gears with the bike on the stand and it shifted fine.
Problem is, the bike wasn’t under a load. After everything replaced after said crash took it for a spin when Rod knock raised its ugly head. Pull the oil pan and found shimmering metal, lots of it!
Motor still in the bike but was looking for upgrade advice for the lower end.

Also, I have been studying inlet and exhaust pressure waves and their effect on hp. I think I understand exhaust back pressure both at the motor to turbo and then turbo to exhaust output and the ratio involved I get that and will be making measurements. I think I understand cam overlap and it scavenges exhaust and brings in a fresh charge of fuel via low pressure from the exhaust track. Understanding the harmonics of these pressure waves still needs study. The one thing I am completely lost with is velocity on the intact track. I understand the convergent and divergent ducting and heat to create velocity on the intake charge but why does that matter when force feeding the motor with 8 psi? Does it mean that the velocity of the fuel charge helps scavenge the exhaust and completely fill (not completely but you know what I’m getting at) the cylinder with a fresh fuel charge?

Anyway, the more I think I understand the more questions I have.. but i am enjoying the journey

I'm certainly no engine design or build expert but I believe most of that goes out the window once it's being force fed. I'm still on my original engine with the stock bottom end and have touched the 10 psi boost range with RCC's intercooler system and Boostane Pro bumping 91 E-free to 101. My Knecum motor I had built over covid will allow 18 psi on plain pump and 26 psi on race fuel. He had Carpenter do the head with all stainless Vance & Hines valves including oversized exhaust valves to spool the turbo quicker.

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Rook, romes.. miss you guys

Hi rspauldi! Yeah, it would sure be great to have Romans back on the regular but we're lucky we have these guys like Fordtech58. I'm learning. Maybe I'll be a ZX-14 turbo guru someday too. We're really fortunate to have this forum.

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Rook! Great to hear you are alive and well.. yeah, I had some health issues and took a lot of time off. But, the juices are kinda flowing again. Sorry to hear bout the gen 1 14, I don’t know the details but I’m assuming all is ok, right? This next build I want to be a bit smarter, to really understand everything instead of just doing mods because of folks saying it works. But focus this time is going to be strengthening the bottom end: I knew it was the weak point so I ran pig rich afr’s (11.0 at wot) and pulled timing.

Gonna be fun learning and taking to you guys along the journey. I’ll get better with pics and info, right now only have audio of rod knock and pics of shinny tid bits in the oil pan.

Oh, one other thing.. I ran the exhaust out to a full yoshi exhaust.. did I create exhaust back pressure? Will it be felt at the turbine wheel and create higher EGT? Will this be felt at the valve and increase temps to the point of detonation. Will it cause back pressure in the exhaust scavenge that will restrict the low pressure during cam overlap from bringing in a fresh fuel charge? I know, I’m nerding out..

Oh, I’ll nerd out a bit more on the intake tract.. lil history, had competition CNC port the head, SS exhaust valves, springs, port throttle bodies to 48mm, then I increased fuel flow w 630 fuel injectors cuz stock ones duty cycle was almost DC flat lined above 10k RPM. Romes did the ECU flash, which was fantastic! I’ve got a different post explaining a seat of the pants review
What I have been studying is the valve size itself is the biggest contributor to flow on the intake not so much the intake port. But then you get into velocity of the air and bowl size at the valve and I get freakin lost.
So, I may look at valve size increase if I can figure out exhaust pressure issues.

Sorry to hear bout the gen 1 14, I don’t know the details but I’m assuming all is ok, right?

I lived so I'd say everything is just dandy. No broken bones, no organ damage, I think my brain still works pretty well but I was out cold. Woke up and crawled away from the wreckage to go to sleep in the road. I'm really sad about the bike though, it fared much worse than I did. It rolled side over side at least three times. I expect to continue for many years with motorcycles and I can't see not having that one back.

This next build I want to be a bit smarter, to really understand everything instead of just doing mods because of folks saying it works.

That's smart. I think the widely accepted mods do work for the most part but only a few make a real noticeable improvement.

focus this time is going to be strengthening the bottom end: I knew it was the weak point so I ran pig rich afr’s (11.0 at wot) and pulled timing.

If you pulled flies on the 06-07 and still didn't have enough bottom end, go with a +4 rear sprocket. That's one of those mods that make a noticeable improvement. Of course, I'd like to get it all from the engine. It's impressive that you experimented with timing and fueling at low rpm. I never got that far but I was pretty astonished with what I achieved with fueling. That bike would pull smooth from 2000 rpm in 6th gear. Maybe not a lot of power but very smooth. I don't know what they're thinking when they do factory tuning. I guess they're thinking about what will pass emissions requirements. I tuned mine pretty lean across the board and still got much improved low end performance so I'm left a little befuddled by factory tuning. Of course, if you're turboed, it's a whole new beast. I don't think a lot of basic mods mean a dang thing at this point.

Oh, one other thing.. I ran the exhaust out to a full yoshi exhaust.. did I create exhaust back pressure?

I'll be interested to hear how that works. RC Turbos makes their own exhausts and they're significantly wider than a NA aftermarket exhaust. Without having much knowledge on turbo yet, I'd say the Yoshi is going to fight your turbo.

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Aw, rook, glad ur ok.. studies have shown concussions have lasting effects. I’ve bad one but which screwed me for couple weeks, I thought I was fine but GF said I was off.
I think my terminology may have misled you when discussing top end and bottom end. Sorry bout that.
I was referring to the mechanics of the motor. Last rebuild I only paid attention to the upper end of the motor. The lower end was completely OEM. This time I’ll take a diff approach

Aw, rook, glad ur ok.. studies have shown concussions have lasting effects. I’ve bad one but which screwed me for couple weeks, I thought I was fine but GF said I was off.

I was teaching at that time and it was the very beginning of the summer break so I had a couple months to recuperate. I'll never know if I suffered brain damage but that crash did leave one lasting change, I didn't touch a motorcycle for two years even though I had the Hayabusa. Even with the new 14R, I can't bring myself to go fast for more than a few seconds. I'm pretty sure I haven't hit 100 mph with it yet and in spite of the big plans for turbo, I must admit going really fast (even on a track) scares me. The turbo is a dream I've had a long time though so I have to do it. Remember Murphy's Law though, sounds like you and I both have learned that by experience. Somehow we have to live around it for as long as we can. ....LOL but maybe you'll see videos of me doing fifth gear wheelies someday! I think I can trust the bike again but I damned sure have no trust in the intelligence of wildlife.

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8 PSI on a stock bottom end is scary. Most turbo zx14 builders wont push a stock bottom end motor past 240hp which is only 4-6 PSI because you'll put a window in the block. And you will run into a lot of detonation issues with that much pressure and compression, unless youre on E85 or C16 I suppose.

Your "Knock" is either from the rods being bent/ovalled/warped (dont start the bike until you open the motor if this is the case) and the bearings spinning. Or your knock is detonation. Or your knock can be 37 other issues based on your setup, unfortunately, none better than the last.

Wossner offers a "mid-compression" Turbo Piston. 10.3:1

You lose about 2 figures of compression. Will help low-end. But you should ideally run lowest possible compression for high hp targets. You will likely also need an intercooler since turbos make the intake air hot once you start pushing high PSI- increasing detonation risk and lowering efficiency.

Research a concept called "Effective Compression Ratio" which will help you reduce detonation.

The second chart is old. New metallurgy and tech has shifted that chart up a line or two. Idea is the same.

* Last updated by: danmin on 6/11/2025 @ 11:19 AM *

Hey Dan, thank you for the info, I appreciate that, and just for ref I live just north of DFW.
Finally got back to the autopsy.. Pulled the cams and head off.. cam lobes look great, journals and caps are good. Cam chain is flexible but saw some daylight between the chain and cam gears, probably just replace with OEM. Head gasket, which is 50 something thick ( to reduce comp) looked good. Here’s the kicker, my stainless steel valves are rusted, bad. Before the accident the bike wasn’t losing coolant. Top of the pistons look good w no coolant in the bore.
The cylinder bores look good so far, hatch marks look very fresh and no groove at the top of the cylinder wall. Pics to come.
At this point I’m looking at 9.5 pistons with thicker dome to ring land clearance but with piston to valve clearance if I decide on larger cam. Was looking at piston coatings.. i.e ceramic. But I’m only looking at max 15 psi boost. So think I’ll shy away for now.
Rods? Going standard length, I don’t think much diff between H or I beam at my target boost level. But open to what you guys think?

Questions:
About to pull the trigger on Maxpeeding 4340 connecting rods. Don’t know anything about the company but the rods are priced right. They use ARP 2000 bolts but and upgrade to ARP L19 is available.
Q: does any one have info on this type of rod? And, is the ARP L19 necessary if staying below 15 PSI boost?

I have always used OEM rod and crank bearings.
Q: is there a benefit to using aftermarket?

I have always used OEM rings.
Q: is there a benefit with aftermarket? Haven’t done much research here and the aftermarket pistons using come with rings.

Q: Ring gap? Honestly didn’t even ck it during last rebuild.

I think that’s it for now, I’m sure there will be more.

I do have a bunch of pics just need to remember how to upload.

Take care,
Later
Rick

The MaxSpeed Rods are tempting since they have a significant price-advantage. But they aren't well documented and are certified to come straight from China. Doesn't mean they'll be junk, but the quality and factors like balance and metal purity will be questionable.

I bit the bullet on Wossner 9.3:1 pistons and their 3/8" Rods. Hurts to buy but I know they'll hold up to whatever I throw at it.

I plan on street riding my bike and keeping the boost "moderate" since you can really only street so much power.

Rob Bush has good prices on OEM Bearings. I think one or two shops offer aftermarket bearings but they are quite pricey and once again, i've never heard of anyone using aftermarket bearings.

Most of the time you'll get new piston rings with your pistons. My Wossner pistons came with their own rings. The supplied rings were a little different than the stock ones. The new ones looked thicker.

I don't remember exactly what I gapped mine to but I used this chart to gap. Better to gap a little larger than too tight. Too much gap and you'll have crazy blow-by and drop compression

* Last updated by: danmin on 6/18/2025 @ 9:09 AM *

Thanks Dan, I was thinking the ring gap would have been larger than 0.006, hum.
Do the Wossner pistons increase the piston to valve clearance so a larger cam could be used?
Do you know if the wrist pin is larger?
Any finally, has the dome to 1st ring land increased?

Good luck with the build, sounds like you’re getting close.

It's a formula. So for a turbo bike it's 0.0006" multiplied by (84mm converted to inches), for example. Pretty sure it is like 0.020" or something like that. Do the math and it'll tell you.

I don't think it'll suit more lift. It's possible but I never researched it. You could always email Wossner.

Wrist pin is stock size but that's not an issue for this platform.

1st ring land is a lot bigger

Ha, maybe I should look at the not so fine print on the formula for the ring end gap. Thanks for straightening me out on that one.

Well, I pulled the trigger on some JE FSR ultra pistons a few minutes ago. Kind of afraid to buy anymore parts until I can get it completely tore down and a good inspection.

Good thinking. I planned on just swapping pistons on mine and keeping everything stock. unfortunately my engine was bad everywhere except the cylinder walls were perfect. If you need any micrometers I'll happily sell for probably 1/4 of what i paid. The JE pistons are nice. that extra coating in the tops of the piston will help with heat management.

Hey Dan, I appreciate the offer on the micrometers but after seeing the price for crank/rod bearings + cosmetic head gasket + engine rebuild gasket set + turbo gaskets I’ll be eating bologna sandwiches for awhile.. gheez!

But, as per usual, another question. Did you go with larger clearances on rod/crank bearings to increase the oil “cushion”? I’ve read a lil bit about it but I’m concerned when in traffic and oil pressure is low will it fill the increased void??

I’ve got the oil pump upgrades and even used a diff oil pressure relief valve which gave crazy oil pressure at start up. Problem is I have this crappy electric turbo oil scavenge pump and it couldn’t keep up with the higher oil pressure and wud die. This created a huge freaking oil mess, could be rectified by going with the RCC mechanical pump but I’m a cheap skate..

I just went with a straight replacement for my bearings. I used Plastigauge and micrometers to double check everything. My original bearing sizes fit perfectly. More clearance in the bearings is an old race thing. Makes sense on a small block chevy that we threw together in the garage but on these bikes things are pretty precise from the factory and is well-engineered. I'd buy 1 pair of bearings of your original size (there is a dot of paint on the side of each bearing indicating size) and plastigauge it to make sure you're in spec. Brock's has a free service manual for these bikes online. If you send me your model year I can shoot it to you.

I would just run 10w-50 oil since it is more heat-tolerant. I am in DFW Texas (I think you are too) and as you know it can get quite hot. Running proper coolant is another important factor. Redline Super-cool is super expensive but is the most efficient coolant on the market.

A used turbo kit will be your best bet for getting a full turbo kit with all the bits and pieces for cheap. There's a couple in the DFW for sale. $2500-7500

I've also got a spare stock thickness Cometic Headgasket I'd part with for half cost or less. I also have some valve springs I think. I accidentally double-ordered a lot of stuff that has ridiculous restock fees.

Just wanted to give a lii update.. so I bought the JE FSR ultra pistons. But, I also cheaped out and bought the MaXspeed rods.. these are not a direct fit.. I had to dremil material directly under the piston pin on the piston to get the the piston pin and rod to line up.. less than a gram..

Not sure what stage you're at on your project but I am learning turbo stuff as I go as well. Every tuner I've talked to/brought bike to say to not run pump 93 above 300hp or so. That E is recommended at that point. My bike made 316hp on a 10lb spring. 15 PSI would probably get you above 350hp, but you'd be fighting a lot of detonation and trusting your fuel a whole lot. Also the boost (with RCC turbo kits at least) kicks in really hard at about 7,000RPM. Goes from 1-3 PSI to full boost in. Whatever your spring is. So traction is certainly a concern there.

Just letting you know that your goals might not be met on pump gas. I'm in the same boat.

Side note- I am selling a MicroTech system for these bikes if you're looking for a fuel system to go with your turbo

I'm glad to see you posting on other threads danmin but do keep your thread updated. You're becoming the new turbo 14R Guru, being that you did all the work yourself. I can't take anything away from Romans but if you're in the scene and doing it now, I need the guidance. I'm getting an old 14R and I'm doing your stuff.

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