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...

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.

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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