Turbo Mag

[DMC]

Hey guys I was glancing through turbo magazine and read a few articles about some cars that have large turbos but run the boost at like 7 or 8 psi and put down very high horsepower numbers, one of which i believe is an acura with 10.5:1 compression and stock internals, but he is putting down about 400 hp. I was jsut wondering why everything i see on here that has 400 hp is at like 23 psi or around there. Does anyone run a low boost setup on a nissan that gives you this much power? I was just wondering if someone can clarify and tell me the benefits of a high compression turbo system and that of a low compression turbo system(which i thought allowed you to bboost more and put out more hp). I dont know maybe im stupid but i havent made a post in awhile and i wanted to get this out of my head, not sure if i made it understandable. Basically i was thinking why not run higher compression pistons on my sr if i can still make big numbers and reduce lag.

[statik]

uhhh 7psi making 400hp on a stock internal motor seems very FALSE

[DMC]

well i dont have the magazine with me now but im pretty sure its an acura cl 10.5:1 compression running 7 or 10 psi putting down over 400 hp

[statik]

im no expert, just seems highly unlikely, tho i dont know the base numbers for that acura either

[Id-]

saying 'acura' and 400hp is like saying 500hp and 'toyota' it could be a BUNCH of different cars
was it an integra? one of the V6 FWD cars?

[S14DB]

My friend has the 'zine. It's the new sedan with the 300hp V6 in it. They boosted it too [email protected]

[OptionZero]

Acura TL A-Spec, 300HP 3.5L V6, SOHC VTEC i think? Might have a 6-spd, I know they have one for the J-series now.

with that much engine, I'm not surprised you can make 400hp on low boost.

[blu808]

whether that is true or not.

Heres what all turbos come down to. CFM (cubic feet per minute).
You can have a huge turbo. that produces so much CFM that 4 psi may be the same as a gt28rs running 19psi. Why? because psi is not how much air is being forced down into the motor. Psi is how much pressure is being put on the manifold by the turbo. CFM's is how much air is being crammed into the motor by that amount of psi.

Also compression ratios have alot to do with it as well. A high compression ratio motor is harder to cram boost into. It is closer to its max cfm capibility than a lower cr motor, so it makes it harder to push air into the cylinders that allready have more air in them to begin with.

A low cr motor is easier to cram boost into because there is not as much air in the cylinders to start with.


There are some side effects though.
Boosting a high cr motor is very prone to detonation. The reason? High cr motors are very hard to control the amount of boost entering the chambers, with the fuel being constant, and the air being inconsistant. The air fuel ratio will tend to jump around. This is when the motor has usually reached its max cfm rating, and lower compression will usually be req to make more power.

Now if you think of a low cr motor in the oposite way then you will understand why they like boost and are more reliable.

Not saying that you might not have known this allready, but thought i would share.

[statik]

Acura TL A-Spec, 300HP 3.5L V6

I could see how that could make an extra 100+ HP from only 7psi, I naturally assumed integra =]

[orion::S14]

A conservative gain on a KA motor that's 9.5:1 and only 2.4liter is about 11rwhp per PSI...add 1 more liter of displacement, even higher static compression, and a few more RPM than your typical Nissan motor (+7500), and you'll get higher gains.

So 7psi can easily add 100rwhp to a BIG 3.5 liter motor.

When you start at 300rwhp, it's easy to get to 400.

Now, start at 155HP, and it takes WAY more PSI to get to 400.

- Brian

[justinhustle]

5zigens tl is up there too, i think 400+ now

[OptionZero]

5Zigen has a TL?! I would have thought they'd make a TSX...
got pix?

I ask because the J-series V6 is an Honda USA engine, built in America and features in domestic market Hondas such as the Accord, CL (deceased), TL, MDX, Odyssey, and RL

The only cars that Japan gets with that is...i believe the Odyssey, though I could be mistaken.

It's basically Honda's answer to the VQ, except SOHC and exclusively paired with FWD/AWD, highly unsporty application.

When will Honda have an RWD chassis to go against the 3-Series, IS300, and G35?

[justinhustle]

i mustve been half drunk still, its a tsx

http://www.5zigenusa.com/images/gallery/5Zigen_Car/5z_Accord_FN01R_1.jpg

http://www.5zigenusa.com/images/gallery/5Zigen_Car/5z_Accord_FN01R_2.jpg

[S14DB]

whether that is true or not.

Heres what all turbos come down to. CFM (cubic feet per minute).
You can have a huge turbo. that produces so much CFM that 4 psi may be the same as a gt28rs running 19psi. Why? because psi is not how much air is being forced down into the motor. Psi is how much pressure is being put on the manifold by the turbo. CFM's is how much air is being crammed into the motor by that amount of psi.

Also compression ratios have alot to do with it as well. A high compression ratio motor is harder to cram boost into. It is closer to its max cfm capibility than a lower cr motor, so it makes it harder to push air into the cylinders that allready have more air in them to begin with.

A low cr motor is easier to cram boost into because there is not as much air in the cylinders to start with.


There are some side effects though.
Boosting a high cr motor is very prone to detonation. The reason? High cr motors are very hard to control the amount of boost entering the chambers, with the fuel being constant, and the air being inconsistant. The air fuel ratio will tend to jump around. This is when the motor has usually reached its max cfm rating, and lower compression will usually be req to make more power.

Now if you think of a low cr motor in the oposite way then you will understand why they like boost and are more reliable.

Not saying that you might not have known this allready, but thought i would share.


What does the C:R have to do with head efficency?

High C:R motors have a higher exhaust velocity to spool a turbo faster than a low C:R motor. The only negative is the higher cyl. pressures that make igniting the fuel charge harder and more prone to detonation. Timing is also a concern.

[blu808]

Timing, is a concern on any motor. It has nothing to do with head flow.

You are correct, a high cr motor will spool a turbo faster.

It does not matter what cr you are running, boost creates the higher cyclinder pressures, more cr will also creat more cp. However it is usually not to the amount a boosted motor would produce.

[Id-]

if you run identical boost levels on an identical engine except different CRs... the higher CR motor will make MORE power...
case in point; plenty of Lexus boys running stock 10:1 compression with a 60-1 turbo making 400rwhp at like 10-12psi, even more with bigger turbos... if they lower the CR with a headgasket they make less power

reason why? the higher compression motor's initial compression is higher, the motor is doing more work... if you raise the boost on an identical low compression motor you can reach the same power levels; but the turbo is doing more work and less the motor...

there are benefits of each idea... take a turbo made for lower boosting numbers, say a 60-1 or 60-trim T04E and run a 9:1 motor and run around 17-18psi you are in the turbo's peak efficiency range still but can make more power with faster spool than the typical 8:1 or 8.5:1 motor

[kidinthehall]

You are correct, a high cr motor will spool a turbo faster.

.


you are INcorrect, as is much of what you posted above that.

Higher compression has MINIMAL effect on where/when a turbo will make a specific boost. It only changes the output that will come from it.

[S14DB]

you are INcorrect, as is much of what you posted above that.

Higher compression has MINIMAL effect on where/when a turbo will make a specific boost. It only changes the output that will come from it.
Where did you get this wealth of knowlege?

[kidinthehall]

i work at a dyno and engine building/machine shop every day.


Where did you get YOUR wealth of knowledge?

[S14DB]

i work at a dyno and engine building/machine shop every day.


Where did you get YOUR wealth of knowledge?
Maximum Boost by Corky Bell

[blu808]

I love how everyone thinks they know what there talking about.

And a higher cr motor will spool the same turbo on the same motor a bit faster than, if that same motor had lower cr.

Also.


"Id- if you run identical boost levels on an identical engine except different CRs... the higher CR motor will make MORE power...
case in point; plenty of Lexus boys running stock 10:1 compression with a 60-1 turbo making 400rwhp at like 10-12psi, even more with bigger turbos... if they lower the CR with a headgasket they make less power"

Yea no shit a high cr motor will make more power at the same bost level than a lower cr motor running the same setup. I was refering to max power output. On a high cr boosted motor. A high cr boosted motor is harder to put boost into and eventually you will reach a point where you cannot put anymore boost into that motor without haveing an inconsistant air fuel mixture, and causing detonation. Thats why people dont run a 11-1cr turbo drag motor. Lower cr motors are alot easier to put boost into, making more overall power, and a more stable air fuel ratio.

Dont you think if you could make all the hp you wanted, on a high cr turbo motor everyone would do it? You wouldnt have barely any lag, great throttle response, and crazy low end power.

duh

[kidinthehall]

I love how everyone thinks they know what there talking about.



the word is they're.


And you took the words right out of my mouth. :bash:

[wootwoot]

so your saying my 12:1 turbo engine is a bad idea?

[dct223]

blu808 is right, high compression cars are harder to put boost into... more prone to problems if u boost high and they wont last. if you researched factory turbo cars, all of the compression ratios are low compared to na cars...

[Id-]

lol hard to put boost into? too much boost causing a messed up air/fuel mixture? wtf?

dude, YOU CAN run race gas on a high compression motor too and crank out more boost.. why? because on pumpgas you reach a certain point where the cylinder pressure is too high and causes detonation; it doesnt have anything to do with being hard to put boost into...

high compression vs low compression has nothing to do with engine longevity if good tuning is used... there's several guys on clublex and supraforums running stock compression on their 2jz-ge's and around 10-12psi on pump gas and have been doing so for years; and putting out large power levels...
now if you're the typical ignorant guy who buys a turbocar and thinks they know everything about them and cranks the boost up too high; the motor is going to go no matter what kind of compression you have...

as for this
I love how everyone thinks they know what there talking about.
Yeah I feel the same way; what you keep saying makes no sense; hard to put boost into? WTF does that mean? :rolleyes:

oh and people DO run higher compression drag motors :) in your linear line of thinking you wouldnt realize a lot of drag cars use straight or supplemental methanol with no intercooler... s. papadakis was a good example

a 10:1 ratio motor can run just as much boost as a 8:1 motor can; now the 10:1 motor is going to grenade easier unless certain tuning is involved (which i have already discussed)... you dont just magically stop the boost because it runs out of room :rolleyes:

I ran a turbocharged Lexus for quite a while myself and ran 12psi all the damn time with no problems on 93 octane pumpgas... now other issues presented themselves such as a crappy intercooler; exhaust leaks, etc... but my motor ran just fine for well over a year and ~15k miles with two different turbokits on the car