hey there everyine...how is everything going....
i was just wondering...why are boosted engines so DEAD off boost....if i were able to run spark control and dial in some decent advance...would my engine feel better off boost.i am running a stock dizzy now and in order to be safe on the top end i have to rotate the dizzy a few degrees ,which in turn lowers the whole advance curve. if i were able to dial the same advance as a naturally aspirated engine when its off boost and then retard it as boost kicks in then would i have the best of both worlds
i was watching Top Gear, the episode where they tested the fq400 against a lambo in they did this test where they set up a test where the evo and some 1.6liter naturally aspirated engine were both put in 5ht gear and then when they floored it...the rented car was quicker.
i dont understand...why couldnt the evo engine pick up while it was off boost...why didnt they dial in some advance to give it some go...obviously a 2.0 naturally aspirated engine is quicker than a 1.6
any ideas guys???
running ms1,v2.2 ans thinking about msns
ignition
Moderators: jsmcortina, muythaibxr
Turbo Lag
You are on the right track , Computer timing control can work miracles
if you learn how to use it .
Quit messing around and get yourself MS-II with the new V-3 Board
and let it control your timing .
And while your at it , trash that Dizzy a put in a Ford EDIS Ignition .
if you learn how to use it .
Quit messing around and get yourself MS-II with the new V-3 Board
and let it control your timing .
And while your at it , trash that Dizzy a put in a Ford EDIS Ignition .
does anyone know if the ford yb engines have ecu controlled ignitiion or not...every where i read about people tuning them...i always hear them talking about fuel only...never spark.....could that be the reason why they drop the compression really low...7.5...they cant tailor the curve as its controlled by the dizzy...or do the brits have cheap gas
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jakobsladderz
- Experienced MS/Extra'er
- Posts: 170
- Joined: Tue Mar 15, 2005 10:08 pm
- Location: Ballarat, Australia
You posted this twice, I replied in the other one..
Compression Ratio, Gear ratio and vehicle mass to engine size ratio..
Generally, turbo engines run a lower compression ratio, meaning that their off-boost power-displacement ratio is slightly less than a NA engine. Especially nowdays where NA engines are pushing 10.5:1 and most turbos are less than 9:1.
Also, an EVO is a relatively heavy car for an NA 2 litre engine, whereas the 1.6 was probably better sized for the smaller engine.
Thirdly, the gear ratio on the 1.6 probably had it close to it's peak power (given its top speed was probably lower) wereas the EVO was probably well down on revs. I'd say a 1.6 on song would be making more power than a 2 litre out of its powerband.
The other thing is that a good NA cam has plenty of overlap, and wont make so much torque at lower revs (enter VVT).. A good turbo cam has much less overlap, so makes better torque low down with the turbo to help out when the revs pick up, so technically they can make more torque all the way through (if properly set-up).
The timing with an ECU will generally be optimised for the operating conditions (maybe with a lean to emissions, nevertheless close for power) and will not be limiting the torque to any great degree. If you run a mechanical advance system with no boost retard, that is a totally different story, but does not apply in the instance you mentioned since they are both EFI.
_________________
Exeter: (noun) the nut or bolt always left over after putting something back together (Douglas Adams, The meaning of Liff)
Compression Ratio, Gear ratio and vehicle mass to engine size ratio..
Generally, turbo engines run a lower compression ratio, meaning that their off-boost power-displacement ratio is slightly less than a NA engine. Especially nowdays where NA engines are pushing 10.5:1 and most turbos are less than 9:1.
Also, an EVO is a relatively heavy car for an NA 2 litre engine, whereas the 1.6 was probably better sized for the smaller engine.
Thirdly, the gear ratio on the 1.6 probably had it close to it's peak power (given its top speed was probably lower) wereas the EVO was probably well down on revs. I'd say a 1.6 on song would be making more power than a 2 litre out of its powerband.
The other thing is that a good NA cam has plenty of overlap, and wont make so much torque at lower revs (enter VVT).. A good turbo cam has much less overlap, so makes better torque low down with the turbo to help out when the revs pick up, so technically they can make more torque all the way through (if properly set-up).
The timing with an ECU will generally be optimised for the operating conditions (maybe with a lean to emissions, nevertheless close for power) and will not be limiting the torque to any great degree. If you run a mechanical advance system with no boost retard, that is a totally different story, but does not apply in the instance you mentioned since they are both EFI.
_________________
Exeter: (noun) the nut or bolt always left over after putting something back together (Douglas Adams, The meaning of Liff)
Exeter: (noun) the nut or bolt always left over after putting something back together (Douglas Adams, The meaning of Liff)
it was a fiat station wagon and i dont think they run as high a compression ratio
a stock cam is used to increase engine drivebility....get maximum torque and maximum bhp as far as possible on the torque-power vs rpm graph
i dont think the evos are that heavy so its safe to say that power to weight ratio is not that big of a factor here...at least at the region of the power band they were doing the test in
a stock cam is used to increase engine drivebility....get maximum torque and maximum bhp as far as possible on the torque-power vs rpm graph
i dont think the evos are that heavy so its safe to say that power to weight ratio is not that big of a factor here...at least at the region of the power band they were doing the test in
do you think it has anything to do with charge dilution due to exhaust reversal into the combustion chambers.....a turbine after all is an exhaust restriction...so maybe when its off boost...there is a large restriction and no manifold pressure...hence you dont get good cylinder "cleaning"
same reason a 2 stroke engine doesnt make huge power like its supposed to...bad scavenging.....
that explains some stuff...i was once driving my car....i had the turbo installed but hadnt altered the timing yet so i had my wastegate hooked up with a wire as to keep it open,to avoid making any boost...but the car still ran badly....
i guess its because the turbo assembly was still a restriction to the exhaust flow and was hindering power...just like a stock exhaust system does
i guess when you add that to the previous reasons...it all makes sense why these engine are bad off boost
any ideas
same reason a 2 stroke engine doesnt make huge power like its supposed to...bad scavenging.....
that explains some stuff...i was once driving my car....i had the turbo installed but hadnt altered the timing yet so i had my wastegate hooked up with a wire as to keep it open,to avoid making any boost...but the car still ran badly....
i guess its because the turbo assembly was still a restriction to the exhaust flow and was hindering power...just like a stock exhaust system does
i guess when you add that to the previous reasons...it all makes sense why these engine are bad off boost
any ideas
A Vacuum Advance Canister will not "retard" the timing under boost .
They only move the timing when below a certain kPa
There are a few exceptions on very old factory installed Turbo engines
that came with a special advance/retard Canisters .
...................Jim
They only move the timing when below a certain kPa
There are a few exceptions on very old factory installed Turbo engines
that came with a special advance/retard Canisters .
...................Jim
'95 GM 4.3 Vortec V-6
Single Plane Intake w/ported GM Throttle Body
Ported Heads , stock roller cam retarded 8 degrees
MS-II 2.6 , V-3 board , MT 3.0
EDIS ignition , Innovate WB 02
250hp , 28mpg @60mph in a 2 ton wagon
Single Plane Intake w/ported GM Throttle Body
Ported Heads , stock roller cam retarded 8 degrees
MS-II 2.6 , V-3 board , MT 3.0
EDIS ignition , Innovate WB 02
250hp , 28mpg @60mph in a 2 ton wagon