GTR Forum banner
1 - 20 of 22 Posts

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #1 ·
right this question is proberly going to show how much of a numpty i am but..
my cars(gtr32) just gone up to tr today and its getting mapped next week all going to plan.ive just put garret 2860-10s tubbies on it,z32s afm,1000cc sard fuel injectors and jun fuel rail,2no tomei intank fuel pumps with 2no fuel feeds one each end of rail,tomei fpr,1.8mm metal head gasket,crank collar,tomei oil pump uprated coilpacks,plugs and engine wise the internals are uprated,87mm wiseco pistons,uprated rods and bearings,and cams,headbolts,sonic damper,pullies and all balanced etc.its got an apexi power fc in it. finaly my to my question,wene the mapper maps the car how does he know the total limit,max power it will run,max bhp?is it knock that he waits to hear?does he just keep wiending the boost up?? it cant be the turbos running out off puff,or could it? cheers guys:thumbsup:
 

·
Registered
Joined
·
3,803 Posts
Would exhaust gas temp also affect max power (probably to a lesser extent, perhaps so much lesser as to be irrelevent))? (genuine question; I'm not trying to be smart, just trying to get smarter!)
 

·
Registered
Joined
·
3,585 Posts
a question also, would you not run the turbos upto there max that the fuel system can supply and then knock the boost back a bit so the turbos are not working past there limit?

so lets say the turbos run out of puff at maybe 1.7 bar, so turn them down to 1.5 ish bar and then finish the map here?
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #5 ·
mapping

thats what i was wondering,to go to the limit of the tubbies and then just wiend the boost bk anotch?the thing is with my set up i dont think fueling would be an issue so im guessing it would just be the limit of the turbos im running?maybe the cams?wene i spoke to rob last year he sugested getting these turbos and mentioned 2bar of boost,does that sound about right:confused::confused:.god wish i was i clever and could understand the setting up of a car:bawling::bawling:
 

·
Registered
Joined
·
3,226 Posts
It's a combination of factors and each one is a trade off.

If it's a road car you want good response with the turbos coming in as early as possible but early response means less top end power, this is to do with cam timing, hence the adjustable cam pulleys.

You want a good air fuel mix throughout the rev range but a leaner mix produces more heat so at high boost you would want it a bit richer to cool piston temps but too rich and you lose power and economy.

More advanced ignition timing can produce more power but means detonation is more likely so this is critical to get right.

So that's why it's a trade off between all these factors and that's where a mappers skill and experience comes into play.
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #8 ·
what bar did you have them apexi tubs run upto? you ran out of fuel when rob mapped them didnt you?
ive got a 2nd intank tomei fuel pump and got 2xfeeds into a jun fuel rail now and 1000cc injectors so shouldnt be aproblem fueling wise now(i hope:D) i know rob got it upto 598bhp but he said he"d maxed the 600cc fuel injectors out not the tubbies mate. i cant remember what boost that was either,soz.
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #9 ·
It's a combination of factors and each one is a trade off.

If it's a road car you want good response with the turbos coming in as early as possible but early response means less top end power, this is to do with cam timing, hence the adjustable cam pulleys.

You want a good air fuel mix throughout the rev range but a leaner mix produces more heat so at high boost you would want it a bit richer to cool piston temps but too rich and you lose power and economy.

More advanced ignition timing can produce more power but means detonation is more likely so this is critical to get right.

So that's why it's a trade off between all these factors and that's where a mappers skill and experience comes into play.
ah i sort of see what your saying.so the mapper has got to get the timing advanced as high as possible just before the det to get the max bhp??
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #11 ·
i take it that figure was flywheel bhp and not wheel?
i think so,ive got the old dino print out some where,if you like i"ll send it to you bud?one thing is for sure if i hadnt of taken my engine out again to fit the crank collar,and have my machanic say to me" if i plan on doing anything else now is the time to do it as he wasnt taking the lump out again", id have left them turbos in my car they pulled like atrain mate.
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #14 ·
mapping

has anyone got the garett 2860-10 turbos fitted to the skyline?and if so could you tell me what bhp they are producing on your car please as going by the garett site they state that they can procuce 460bhp each(920bhp for 2no).is this realistic figure with the right fueling,cooling set up,and agood mapper?? cheers:thumbsup:
 

·
Registered
Joined
·
265 Posts
turbo's are chosen for their amount of air they can squeeze into an engine like say 100lbs/min


and you get approximatly 10hp per lbs of air ingested.... granted you mapped correctly and avoided knock etc....


but other factor comes in that could influence the power producing outcome... such as ambient air temp.... altitude etc..... colder ambient air makes it easier to produce power due to the fact that there is more molecule of air per the same quantity of air ingested by the turbos ..... the difference in altitude also changes outcome......
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #16 ·
mapping

turbo's are chosen for their amount of air they can squeeze into an engine like say 100lbs/min


and you get approximatly 10hp per lbs of air ingested.... granted you mapped correctly and avoided knock etc....


but other factor comes in that could influence the power producing outcome... such as ambient air temp.... altitude etc..... colder ambient air makes it easier to produce power due to the fact that there is more molecule of air per the same quantity of air ingested by the turbos ..... the difference in altitude also changes outcome......
so porting and polishing,bigger exhaust,intercooler,exhaust,all the little bits add up,but make more of a difference wene lets say its a nice frosty morning and chillyer outside better than it being a hot sunny day?if so should be fine here in uk as always raining and cold a:chuckle::chuckle:
 

·
Registered
Joined
·
265 Posts
exactly... but you got to set a safe tune with some margin for error since you wont see antartica like temperature on a daily basis .... so in short ... tune for how and when you will drive your car
 

·
Premium Member
Joined
·
1,380 Posts
Discussion Starter · #18 ·
It's a combination of factors and each one is a trade off.

If it's a road car you want good response with the turbos coming in as early as possible but early response means less top end power, this is to do with cam timing, hence the adjustable cam pulleys.

You want a good air fuel mix throughout the rev range but a leaner mix produces more heat so at high boost you would want it a bit richer to cool piston temps but too rich and you lose power and economy.

More advanced ignition timing can produce more power but means detonation is more likely so this is critical to get right.

So that's why it's a trade off between all these factors and that's where a mappers skill and experience comes into play.
so am i right in thinking that the higher the boost the more fuel needed and less economy but more power or less power?so wene your not on boost do you get bore wash with to much fuel getting put in or is that all set up threw the ecu not to?cheers..
 

·
Registered
Joined
·
3,803 Posts
ecu makes sure fuel amount injected is correct for a given situation, based on things like airflow (or boost pressure), temperature, rpm, throttle position etc.

You're right; higher boost = more power, as long as enough fuel is also used. Problem is that higher boost increases the temperature of the air too, hence intercoolers etc.
 

·
Registered
Joined
·
265 Posts
so am i right in thinking that the higher the boost the more fuel needed and less economy but more power or less power?so wene your not on boost do you get bore wash with to much fuel getting put in or is that all set up threw the ecu not to?cheers..

yes....


lets look at it this way....


boost is represented in psi or pressure ratio.....

and a turbo's power cappacity are looked at in lbs/min of air it can flow at a certain desired pressure ratio..... the bigger the turbo you look at the more they will flow.
 
1 - 20 of 22 Posts
Top