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Port and polish worth something???

2K views 38 replies 6 participants last post by  John Z Williams 
#1 · (Edited)
Port and polish worth something? Gain 20whp&30wtrq

Here is the before and after on the dyno. The after is with the porting of the exhaust manifold and the turbo housings and Nicks new intake pipe. I have too much air now and will have to get another ecu most likely, the mixture is on the lean side again, I just can't leave well enough alone. Darn, now I know why a custom tune is so valuable in high hp applications....:( I just found out I got some bad gas from the small station in Berthod and its 93 octane... It was stuttering on the dyno and on the way home, topped it off with Shell 91 and the miss and stuttering went away. Just my luck, now I have to dyno all over again... I think the mixture is acurate anyway. Mr. rich ecu going back in for the next test. There was snow and temps in the 30's today. I gained 20whp and 30wtrq by the end, but the a/f is a little lean.
John
 
#4 ·
Thanks, yea Nick made a custom t25 intake pipe for me and made it as big as possible. Its much larger on the inlet side and a little larger on the outlet side. I kind of wish I had found a 9000 t25 turbo core to make the housings from for my t28/gt28r turbo. The 9000 t25 has a 6cm exhaust housing and a 2" id for the compressor side housing. My stock t25 inlet side compressor housing is only slightly larger than the stock 1.75" id. That extra 1/4" id could make a big difference in top end flow. I might lose some spool-up time though, its always a trade off, good spool to good power. Finding that perfect compromise is the key to a good spooling system. The largest plus in this whole entire porting deal is the smooth transistion from no boost to boost. It really smoothed it out and the power is so smooth my dyno driver said wow, the steering wheel does not shake or shimmy at all, you really made it transistion smoothly. It feels smoother all around.... Now what about that intake side??? hhhhmmmmmm

JZW
 
#5 ·
John,

You did a port and polish of the exhaust side, and altered the intake side, so you really don't know which helped you, or to what degree. There are too many variables to determine a direct cause and effect.The port and polish might have only yielded 1 hp, and the intake pipe the other 29.

Or vice versa.

But the fact that the A/F has changed is a strong clue that the intake change might have had the biggest effect.
 
#7 ·
Yea, I thought about that and you are right, there is no way to know for sure which change had the greatest effect, but after talking to some tuners and racers at the dyno shop, they convinced me its mostly from the porting/polishing. The intake pipe is only 2mm larger than the stock one:eek:

It is actually smaller for a longer period, the last 3" of the intake pipe is 1.75id
the stock pipe is 2"id all the way to the very end or the last 1" or so, it goes down to a 1.75id.

The only way to know for sure is pull the new pipe off and put the stock one back on and try it again. That would tell more of the story and let me know if its mostly the pipe or mostly the porting or half and half or whatever it is. What I do know is the smooth transistion from no boost to boost is from the porting as this is the most common reason to have the head ported/polished, its about drivability more than the 10hp gain you may see. That is what makes me smile the most, the nice smooth transistion....
John
 
#8 ·
Exhaust side changes generally help spool-up, so it makes sense that you're seeing a quicker and more linear boost transition...

Hunt, that was a pretty interesting and thorough series of tests. That's the type of detailed analysis that generates serious data. The surge issue is one that I see at low rpms with my 16T, using a K&N panel and a 2.5 inch intake from filter to turbo. The spool-up is extremely quick -- about 2200-2500 rpm -- but unless I'm pushing it, I hear the fuff-fuff-fuff-fuff of compressor surge when I let off the gas. Doesn;t happen often, though, so I'm not worried about it...
 
#9 ·
Yea, that was a lot of great information hunt! I too see some surging on occasion, its when I start to boost and then let off it will puff, puff, puff...

I was lead to believe that can be adjusted with your bov spring rate. I have reduced mine from all the time to almost never with less spring pressure...
John
 
#11 ·
Thanks a lot, that is great information. I would like to discuss some of the issues I am having with my car and the a/f and power and would like to know if you are up to some questions from me? How should I communicate? email, pms?

Great work on your polish job, very smooth and clean! Sure looks like a lot of work to get that intake pipe to fit on the gt2871 turbo in the stock location.
That compressor outlet looked awesome, I did not go that far as I was told to watch out and not get the compressor outlet too thin and compromose the strength of it... Thanks again,
John
 
#12 ·
John Z Williams said:
I would like to discuss some of the issues I am having with my car and the a/f and power and would like to know if you are up to some questions from me? How should I communicate? email, pms?
Let's here them. If it gets too off topic we'll take it eslewhere, but everyone tends to benefit from these.

John Z Williams said:
Great work on your polish job, very smooth and clean!
I'll be honest, I got real fed up going through so many bits and getting nowhere. Some of those required professional grade silly-putty to finish.;)

John Z Williams said:
Sure looks like a lot of work to get that intake pipe to fit on the gt2871 turbo in the stock location.
Way way too much time effort/cutting/fitting/welding/wash/rinse/repeat.

John Z Williams said:
That compressor outlet looked awesome, I did not go that far as I was told to watch out and not get the compressor outlet too thin and compromose the strength of it... Thanks again,
John
That's one thing I didn't touch for the same reason. I'm not sure what you are talking about. Unfortunatly, that site has lots of stuff that was many many revisions ago.
 
#13 ·
Ok, one question is at what point would you say its too lean of an a/f mixture?

I go up from 11.5/1 to 12.8/1 between 4000rpm and 5000rpm, then I start to fall and am at 11.1/1 by 6000rpm. I am thinking this is still too lean and although the power feels strong, you can see that the power curve line falls off right at the point were it gets close to 13/1. The dyno shop tech felt the a/f was the reason and I needed to get it back down to 11.5/1 no matter what. I wanted a second opinion for fi cars. What is considered the optimal a/f for our cars and would you say its really not safe to hammer my car with it being close to 13/1???

Second question is have you had a dyno done in Denver since your mods and turbo upgrades. I would be interested to hear how your car does on the dyno with the gt2871 turbo???

Third question you answered somewhat. How much trouble is it to get the inlet pipe to fit on the gt2871 turbo with stock manifold? Is there an adaptor plate to help with that and what would have to be done to make the exhaust side fit my existing 3 bolt pattern down pipe? Is there an adaptor to make it fit my existing dp that I have now? Where can I find some of these v-band adaptors that may enable me to use the gt2871 turbo with my stock exhaust manifold???

Thanks for any help you can be on these issues with my car. In your opinion, how does that power/torque curve graph look to you? I had some bad gas, do you think that could be part of the up and down of the power curve??? It stumbled bad on the first dyno run and did it after I left the shop, I filled up with Shell gas and the missing went away...?
John
 
#14 ·
John Z Williams said:
Ok, one question is at what point would you say its too lean of an a/f mixture?
John Z Williams said:
I go up from 11.5/1 to 12.8/1 between 4000rpm and 5000rpm, then I start to fall and am at 11.1/1 by 6000rpm. I am thinking this is still too lean and although the power feels strong, you can see that the power curve line falls off right at the point were it gets close to 13/1. The dyno shop tech felt the a/f was the reason and I needed to get it back down to 11.5/1 no matter what. I wanted a second opinion for fi cars. What is considered the optimal a/f for our cars and would you say its really not safe to hammer my car with it being close to 13/1???

Second question is have you had a dyno done in Denver since your mods and turbo upgrades. I would be interested to hear how your car does on the dyno with the gt2871 turbo???


Third question you answered somewhat. How much trouble is it to get the inlet pipe to fit on the gt2871 turbo with stock manifold? Is there an adaptor plate to help with that and what would have to be done to make the exhaust side fit my existing 3 bolt pattern down pipe? Is there an adaptor to make it fit my existing dp that I have now? Where can I find some of these v-band adaptors that may enable me to use the gt2871 turbo with my stock exhaust manifold???


Thanks for any help you can be on these issues with my car. In your opinion, how does that power/torque curve graph look to you? I had some bad gas, do you think that could be part of the up and down of the power curve??? It stumbled bad on the first dyno run and did it after I left the shop, I filled up with Shell gas and the missing went away...?

John



I just received the proverbial turd in the inbox. I have to get this taken care of ASAP, if I have time I'll give you a full reply later this evening.


Basically A/F perfect = 12. 11.3-12.7 are OK, but I'd much rather run rich than lean.


Dyno's yes and no (yes after mods, no after GT2871R)


Under no circumstances should you put a GT2871R in the stock location, or you won't have any dyno's ;-)
 
#15 ·
Hunt-Great link. Now children, what Have we learned if we read that thread? :p Open end intakes suck "hot air". Also, don't go throwing that stock air box away.:nono; I subscribe to autospeed online mag and they also have a great write-up on stock air filter setups-the bigger the better. As Mike pointed out and others, a K&N drop in filter will give you more HP, but at a cost to your engine if your not cleaning the filter every 1000 miles or so. I think I'm going to try the drop in filter route, but add some form of a secondary screen/foam setup off the suction pipe.
 
#16 ·
John Z Williams said:
Ok, one question is at what point would you say its too lean of an a/f mixture?
Anything over 13.7:1 is too lean, thats what I have been told for a FI car.

John Z Williams said:
What is considered the optimal a/f for our cars and would you say its really not safe to hammer my car with it being close to 13/1???
Like said 12.0:1 is optimal. Much less than 11.0:1 is too rich. The down side to too rich is poor fuel consumption and increased carbon monoxide emissions.

John Z Williams said:
Second question is have you had a dyno done in Denver since your mods and turbo upgrades. I would be interested to hear how your car does on the dyno with the gt2871 turbo???
I've dyno'd a few times at various stages, not after the GT2871R mainly because I can't boost past 1.4 Bar in the mid range without serious surge. I've run the car dead-nuts (wastegate closed) and it will get past the surge issues in gear 3 with only a small hiccup at ~4K RPM. Gear four the hicup is longer and more difficult to "power through." No idea about gear 5 as that is approaching 125-140 MPH. Dead nuts it'll boost to ~1.85 BAR and hold steady. I've said it before, but there is no need for this kind of power on the streets. Even at 90-100 MPH the car wiggle-waggles all over the (track) when on full boost, I can light the tires at 75 MPH. :evil:

John Z Williams said:
Third question you answered somewhat. How much trouble is it to get the inlet pipe to fit on the gt2871 turbo with stock manifold?
With my set up there is no inlet pipe. I've welded a very custom aluminum cone-elbow on the compressor housing. see below. There really is no room for a turbo this size. I was stuck on trying to find the best bolt-on for our cars possible as I was trying to bring it to market. That bill is filled by JAK's Big T28. I've not ruled my solution out, but I think it's best to rule out the bugs before I say go either way. If i only have a software issue then all is good. Everyone will know if this takes place.





John Z Williams said:
Is there an adaptor plate to help with that and what would have to be done to make the exhaust side fit my existing 3 bolt pattern down pipe? Is there an adaptor to make it fit my existing dp that I have now?
I have two, unknown to me, but these things apparently don't exists. We've called all kinds of people including Garrett and they don't have a p/n for them. See what I mean?



John Z Williams said:
Where can I find some of these v-band adaptors that may enable me to use the gt2871 turbo with my stock exhaust manifold???
You can call ATPturbo. However, I would highly highly highly (get the idea?) recommend you don't go this route. This turbo requires a better intake than what I'm using. A 4" necked down to 3" is what I'd recommend. There is exactaly zero additional room for this. Get a new manifold that positions the turbo closer to the battery, allows for a nice 3" elbow for the intake. This will require a new custom manifold, downpipe, and intake. After all the work I put into the manifold and DP I didn't want to have to redo, especially trying to establish the ultimate bolt-on turbo kit.



Here are some shots of the compressor housing pre me toying with it, and how much room there was (none). Note the AC housing is about even with the shaft.





John Z Williams said:
In your opinion, how does that power/torque curve graph look to you?
I really like the pre porting curves. I'm sure you'll be able to get this setup figured out. The first dyno you posted way back when was garbage, the power fell above 5500 RPM and I really didn't like the TQ spike mid range. I'm sure it felt fast, but traction is a royal PITA with a spike like that. No idea what was causing your notchy curves this time. Bad RPM sensor/reading (?)

I hope some of this helps. I'm sure some of it is not what you want to hear, but these are my thoughts/feelings/findings. They may change when I have the time to mess around. Ski season is almost over (only two more weeks) and then I get my Sunday's back.
 
#17 ·
Thank you very much for all your help on this matter. I really appreciate all the pictures and advice to this larger turbo. I will have to admit that I have never had the time or money to play with a tuner car and spinning the wheels at 75mph sounds like fun to me. Like you said, it does not help the speed of the car and it will get old fast and then what? I do not want to ruin my tires evey 2 months and have my tranny snap and have to do a big expensive clutch that I will surely need, then the new manifold, then the new turbo, then the new inlet pipe then all the fabrication of the oil/coolant lines, then the time and frustration to install it all... That would be at least 3000 bucks... Shoot, I might as well get down and dirty and shoot a 50-75 shot of nitrous and then I could keep the decent spool up of my turbo and then have the extra 50-75bhp on occasion whenever I get the need for speed:p
I think I could do a wet shot of nitrous for about 500-600 bucks including an additional fuel pump to re-route the return line back into the throttle body, then mix fuel and nitrous there and get an even atomizing mix into the intake manifold. One problem is if you are too close to the manifold it most will get sucked into the first runner and cylinder 4 or 1? then leave little for the rest of the cylinders. This sound very dangerous and having most of a 50 shot going into one cylinder would be catastrophic:evil:
Thanks again,
John
 
#18 ·
Shoot, I might as well get down and dirty and shoot a 50-75 shot of nitrous and then I could keep the decent spool up of my turbo and then have the extra 50-75bhp on occasion whenever I get the need for speed:p
I think I could do a wet shot of nitrous for about 500-600 bucks including an additional fuel pump to re-route the return line back into the throttle body, then mix fuel and nitrous there and get an even atomizing mix into the intake manifold. One problem is if you are too close to the manifold it most will get sucked into the first runner and cylinder 4 or 1? then leave little for the rest of the cylinders. This sound very dangerous and having most of a 50 shot going into one cylinder would be catastrophic:evil:
Thanks again,
John
Switch to a T7 intake manifold. It's significantly larger overall, with bigger intake runners that taper down to fit the head. Most importantly, it uses a diffuser to ensure equal distribution of air. Only thing you'd need to do is to make an adapter plate of phenolic plastic to use your T5 throttle body

Put the wet shot nozzle in the throttle-body intake elbow and you shouldn't have a problem.
 
#19 ·
I was not aware of that, the t7 is much larger? That would surely help things with the boost pressures I am running and then again with the diffuser to even up the air mix... I got one for you... I had some missing on the dyno, I checked it last night, the plugs are shot again, they are bad. I looked into the holes with a light and looked at the top of the pistons... Pistons 1 and 3 were clean as a whistle, I could read the numbers on top and they were silver. Pistons 2 and 4 were black with loads of carbon built up on them. Any thoughts as to why two would be so clean and the other two be so dirty? I mean I could see what looked like chuncks of carbon built up, I tried to blow out with compressed air, but its on there... I guess when I pull the head, I will clean them then, is this blow by from bad piston rings or maybe my lean mixture causing carbon build up and if so, why half the motor???

John
 
#20 ·
The central air chamber AND the individual runners are bigger on the T7 manifold. That's one of the reasons the T7 head flows better than the T5. You'd need to do some minor modifications to get your T5 fuel rail to fit, and that adapter plate I mentioned.

Dunno about the odd difference in carbon buildup. That's pretty odd to see such a difference, because you'd usually see an even carbon buildup (dry, kind of sooty or flaky) if you were running really rich for a while. An uneven buildup might be a misfiring DI....

This is a real mystery....
 
#21 ·
Well, I did have to put in the lower half of the di when I bought the car and it was missing badly and then the new lower di section got rid of the miss... It could have been missing for ever, who knows. I am going to replace my plugs again and see how it runs. It was missing again this morning under high load. The plugs look shot. It was running very rich after I replaced my bad fuel pump, went below 10 off the scale on the first dyno after the pump repair. I will look into this and get back on the dyno. I would still venture to guess the a/f is still too high and I should go back to the other ecu that has much more fuel. It may actually turn out to be just right now that I am running more boost and pumping more air into the head..... Its a never ending game of trial and error. Sure wish I had a piggy back laptop that I could adjust my fuel maps with. I watched Nick tune a Supra with his laptop on the dyno, pull after pull and adjustment after adjustment... Two boost settings, first 1 bar, car made 445whp and then with second setting, a flip of a toggle switch and bam 1.4 bar and 513whp.... Now that car sounded sick!!! The turbo was as big as some I see on big diesels!!! I would like to feel the power of a 513whp Supra as you open her up. It would start to spool at 4k, but would not really come alive and reach full boost until about 5000rpm, then run like a raped ape until 7k... That is way too high for good street drivability, but on the track, look out;)

John
 
#22 ·
John Z Williams said:
Well, I did have to put in the lower half of the di when I bought the car and it was missing badly and then the new lower di section got rid of the miss... It could have been missing for ever, who knows. I am going to replace my plugs again and see how it runs. It was missing again this morning under high load. The plugs look shot. It was running very rich after I replaced my bad fuel pump, went below 10 off the scale on the first dyno after the pump repair. I will look into this and get back on the dyno. I would still venture to guess the a/f is still too high and I should go back to the other ecu that has much more fuel. It may actually turn out to be just right now that I am running more boost and pumping more air into the head..... Its a never ending game of trial and error. Sure wish I had a piggy back laptop that I could adjust my fuel maps with. I watched Nick tune a Supra with his laptop on the dyno, pull after pull and adjustment after adjustment... Two boost settings, first 1 bar, car made 445whp and then with second setting, a flip of a toggle switch and bam 1.4 bar and 513whp.... Now that car sounded sick!!! The turbo was as big as some I see on big diesels!!! I would like to feel the power of a 513whp Supra as you open her up. It would start to spool at 4k, but would not really come alive and reach full boost until about 5000rpm, then run like a raped ape until 7k... That is way too high for good street drivability, but on the track, look out;)



John
No way that is too much power for the street! Ask me how I know?:cheesy:
 
#24 ·
John Z Williams said:
Thank you very much for all your help on this matter. I really appreciate all the pictures and advice to this larger turbo.
:D No worries, ask and yee shall receive.

I'd guess the previous bad DI was the cause of your build up. I thought I had read somewhere about an aerosol piston cleaner..........Anyone have any idea what I think I might have thought I read? :confused:

If you want a good chance of getting that crap off of there I'd think 99% isopropyl or maybe even full strength BG44K would have a chance. I'm sure the car would run like crap until that stuff gets pushed through, but it might work. The isopropyl will eat rings so be careful. You might have better luck letting the BG sit on the piston(s) for awhile.

BTW, the T7 Intake manifold is much larger and uses double-decker-runners. Can anyone find the pics to demonstrate?
 
#25 ·
Maybe that is what I am experiencing now??? It misses real bad under heavy load, say wot at 2500rpm in third. If I go wot in second gear, and run through the miss, it cleans out and runs smooth on the top end. After I do that, it will run perfect for a day or so. Then it gets clogged up and starts missing again, I clean it out with high rpms and it goes away for a day or two. It sounds like I could be getting carbon deposits clogging up the system... I will run some more bg44k through it, I guess I could try and let it soak on top of the pistons...

Thanks, John
 
#26 · (Edited)
CO-Saab said:
BTW, the T7 Intake manifold is much larger and uses double-decker-runners. Can anyone find the pics to demonstrate?
Ask and ye shall receive...:cool:



To use this on a T5, you only need the manifold and the gasket -- bottom two bits -- not the spacer and secondary gasket (which I think might only be on California cars). These weren't on my T7 engine.

Here's the "spaghetti strainer" air diffuser I mmentioned earlier:



It's very doable....This is what I run in my car.
 
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