To those with ported heads,

[rerb]

Hi, im building a better motor for my boosted b12, and am currently sizing turbos for my power goals (~400).

I'm going mtc turbo pistons and maxpeeding rods with all the APE head/crankcase hardware with an efi conversion.

According to my calculations I'll need about 38 psi of boost to achieve this with a pressure ratio of ~3.5, and mass flow rate of about 33 pounds of air/min.

These are very fucky numbers and after a few hours of searching I couldn't find a turbo where the compressor map doesn't plot my setup at, or beyond the surge line. I can't run e85 too often or methanol because it's not available here (trying to keep it a streetbike) so I can't do much with fueling to adjust those numbers.

But I've been told a ported head will make the same power with less boost, I'm going to send mine off to APE for an oversized valve job and port, but I still want to know how much it'll help so i can order the right turbo as soon as I can and swap the flange on the manifold.

So guys with ported heads, what boost and horsepower are you at??

Thanks!

[Gixer1460]

I was at 370hp using 30/26 valves but engine is 1460cc and waaaaay less boost than that. EFI'd and intercooled.

I don't think those numbers are practical for a 'street bike' ie. using unleaded petrol ! If Busa's can top 500hp with 1300cc and unleaded i'd spec one of those turbo's - a GT30/71 or similar should work but unless you go large on the capacity, I think you'll struggle!

[clivegto]

Two turbo bikes on the road at the moment both with big valve heads both ported by Rodger Uperton. Tdo4l turbocharger running 16psi made 250hp. IHI vf23 running 14psi  made 260hp. Completely different bikes to ride. 

[rerb]

1 hour ago, Gixer1460 said:

I was at 370hp using 30/26 valves but engine is 1460cc and waaaaay less boost than that. EFI'd and intercooled.

I don't think those numbers are practical for a 'street bike' ie. using unleaded petrol ! If Busa's can top 500hp with 1300cc and unleaded i'd spec one of those turbo's - a GT30/71 or similar should work but unless you go large on the capacity, I think you'll struggle!

True, real number on the daily tune will probably be around 350. I do have watermeth and low ambient temps where I am, but knock could become an issue. On race days, I will have it on e85 which is a pain the ass to get here, but possible for events. That should be enough to run 400 without cooking anything (I hope). Looking at the compressor map for the gt30/71 if I can get enough efficiency with a ported head, that should be a pretty damn perfect turbo what I'm looking for.

 

4 minutes ago, clivegto said:

Two turbo bikes on the road at the moment both with big valve heads both ported by Rodger Uperton. Tdo4l turbocharger running 16psi made 250hp. IHI vf23 running 14psi  made 260hp. Completely different bikes to ride. 

Wow, im making 250 at around 21 psi so that's good to see the effect a ported head can have. At that rate I should be able to run low 30s and still make power, thanks for that info 

[Arttu]

Few notes:

• As rule of thumb you need 40lbs/min air flow for 400hp. Naturally this can vary in reality but if you don't have better info from your engine setup 10lbs/min per 100hp is a good guess.
• With sensible turbo setup you should be able to reach 400hp with less than 38 psi boost. I guess it should be doable with 30 psi even without any radical engine modifications. A stock Bandit 1200 engine that I tuned made about 260hp with 0.9 bar / 13 psi boost. Although that was on E85 but it shouldn't make huge difference compared to pump gasoline.
• Yes, porting the head can result more power at the same boost. With the cams the head is the most important factor on engine's "base power" capability. So ultimately you can get pretty significant improvements on "less tuned" engines like B12. But that can be tricky if you are aiming for big gains. The porting, cams and the whole package must work together and in the worst case the results can be disappointing if you don't get these right. But with milder porting something like 10% improvements should be relatively easily achievable.
• As mentioned above a Garrett GT3071 or GT3076 should be good choices for your targets. Or for lower budget a Holset HX35 should be fine too.

As side note all oil cooled turbo engines with ported heads and hotter cams that I have tuned by this far have been somewhat disapointing. I think that mentioned stock B12 engine has resulted better boost/power ratio than any of those. I guess that the main reason for this has been (too) low compression ratio on those tuned engines. But in any case the point is that just throwing in some tuning parts don't necessarily result more power...

Edited September 10 by Arttu

[peter1127]

imo for a streetbike 400hp is too much.  The wheelbase and amount of lowering needed to keep that under control doesnt fit my definition of a streetbike. The lower compression to use pump fuel and larger turbo needed to reach your goal will make the low rpm range pretty poor. Not ideal on a streetbike.

I would aim for 300hp, keep my money and use the stock head. Or maybe upgrade to a GSXR head & cams for a fraction of the cost. 

[clivegto]

For me it's about how the bike takes of when coming on boost not total HP and I agree that 300hp is still alright for road use much higher  isn't really sreetable. Allspeeds had just over 400hp on carbs but had to bring it down to around 300hp for road use and I've ridden with him on my older setup before he sold it. 

Edited September 10 by clivegto

[Fredrik_Steen]

Look for a gtx3071, you can find them on aliexpress for a decent price. Less oil required for the ball bearing version that will be beneficial for the engine 

[rerb]

10 hours ago, Arttu said:

Few notes:

• As rule of thumb you need 40lbs/min air flow for 400hp. Naturally this can vary in reality but if you don't have better info from your engine setup 10lbs/min per 100hp is a good guess.
• With sensible turbo setup you should be able to reach 400hp with less than 38 psi boost. I guess it should be doable with 30 psi even without any radical engine modifications. A stock Bandit 1200 engine that I tuned made about 260hp with 0.9 bar / 13 psi boost. Although that was on E85 but it shouldn't make huge difference compared to pump gasoline.
• Yes, porting the head can result more power at the same boost. With the cams the head is the most important factor on engine's "base power" capability. So ultimately you can get pretty significant improvements on "less tuned" engines like B12. But that can be tricky if you are aiming for big gains. The porting, cams and the whole package must work together and in the worst case the results can be disappointing if you don't get these right. But with milder porting something like 10% improvements should be relatively easily achievable.
• As mentioned above a Garrett GT3071 or GT3076 should be good choices for your targets. Or for lower budget a Holset HX35 should be fine too.

As side note all oil cooled turbo engines with ported heads and hotter cams that I have tuned by this far have been somewhat disapointing. I think that mentioned stock B12 engine has resulted better boost/power ratio than any of those. I guess that the main reason for this has been (too) low compression ratio on those tuned engines. But in any case the point is that just throwing in some tuning parts don't necessarily result more power...

Great info, I used Garrett's equations to calculate my numbers on pump gas, probably not super accurate. Might skip the porting and just get the valve job done, I already know the guides, seals and valve seats are a bit worn from oil burning and "eh" leakdown test results.

 

7 hours ago, peter1127 said:

imo for a streetbike 400hp is too much.  The wheelbase and amount of lowering needed to keep that under control doesnt fit my definition of a streetbike. The lower compression to use pump fuel and larger turbo needed to reach your goal will make the low rpm range pretty poor. Not ideal on a streetbike.

I would aim for 300hp, keep my money and use the stock head. Or maybe upgrade to a GSXR head & cams for a fraction of the cost. 

I agree, I want 400 for going to 1/4 ,1/8, and 1.5 mile events where I plan to swap out the rear for a longer swingarm and grippier tire, and run e85. Pump gas tune will probably be 310-340. I'll have to figure out compression ratio for a setup with low 300's on pump and ~400 on E, i did shave the deck of the cyls down a mm on 20 psi with just busa pistons and the bump in low/mid end power is something I don't want to miss too much of by going with a real low CR. I hit 260hp+ boost creeping on 26 psi, but 10:1 AFR and 20 deg of timing pulled out which i believe is a pretty conservative tune. MTC says 10:1 with their turbo pistons and I think im around 9.8-10:1 now, so it shouldn't be too bad. 

 

2 hours ago, Fredrik_Steen said:

Look for a gtx3071, you can find them on aliexpress for a decent price. Less oil required for the ball bearing version that will be beneficial for the engine 

I was under the impression BB turbos would cook themselves pretty fast without coolant, but if not that's definitely the better option 

[Arttu]

9 hours ago, rerb said:

Great info, I used Garrett's equations to calculate my numbers on pump gas, probably not super accurate.

What kind equation that was? On quick look from their tech notes I found this:

"As a very general rule, turbocharged gasoline engines will generate 9.5-10.5 horsepower (as measured at the flywheel) for each lb/min of airflow. So, an engine with a target peak horsepower of 400 Hp will require 36-44 lb/min of airflow to achieve that target."

As said this 10 lb/ min per 100hp is a rough generalization but still probably best starting point unless you have some real efficiency data from your engine setup. Which people rarely have...

310-340hp on pump gas and 400hp on E85 sounds like much more realistic target than 400hp on pump gas I think you can achieve the pump gas target with 1.2-1.4 bar boost. And with water injection I would probably aim for 9.5-10:1 compression for that. More importantly, try to get the squish band gap (piston crown - head) between 1.0-1.5mm. I think that's pretty important for efficient combustion. On E85 you probably can use up to 2 bar boost with that compression, or even more. At least with water injection.

Based on what I have seen and heard quality of those cheap copy turbos seem to vary a lot. On both efficiency and longevity. And ball bearing versions seem to vary even more than plain bearing ones.

[94RF1146]

Watch Richard's video...

 

[Reinhoud]

I don't have high hp numbers on my bike, but I do have experience with different heads, one ported, the other gas flowed.

The gas flowed head has a more aggressive throttle response.

 

When I had my head ported I hardly gained any power, I did get a very nice/flat torque curve.

[Arttu]

On 9/18/2024 at 2:45 PM, Reinhoud said:

I don't have high hp numbers on my bike, but I do have experience with different heads, one ported, the other gas flowed.

What you mean by ported and gas flowed? As I understand it "porting" means all modifications done for the head ports.

[Reinhoud]

11 hours ago, Arttu said:

What you mean by ported and gas flowed? As I understand it "porting" means all modifications done for the head ports.

As I see it; Gasflowed is a more serious job over porting. With gasflowing the flow is measured on a bench.

If you look at both heads, the ported head has bigger ports, the gasflowed one has actually slightly smaller ports, but there's way more time invested in making the ports a certain shape, not just taking sharp edges off and make the ports bigger.

 

[Arttu]

Ok, so in other words better and worse porting 

[Gixer1460]

You say 'Zee', I say 'Zed' - porting / gasflowing - two words to describe the same thing IMO!