Would it be worth it to put an mevi on a turboed maxima that cannot have its rev limiter raised?

I know NA it seems like its reall y not worth it. but what do you guys think? Of course i have a 99 se-l so i'm using the emanage but i cannot raise the rev limit with this thing. Around 5000 - 5500 rpms what kind of gains are you guys seeing with the mevi?

 

I think turbo 97 was getting like 30-35 more horsepower in the 5500-6700 range.

 

Don't waste your money on MEVI or porting the head or any of that BS.

Just turn up the boost...it's FREE...as long as your setup can support it that is.

 

Redmax: without a rev limiter adjustment, YES it's still worth it. But look into having a custom one made instead.

 

The VI will lower your HP in the lowend. You would it would probably do you some good on launching if you are considering doing the quarter. For highway runs you will get big gains from it.

 

Okay, why not just turn up the boost?

 

From what I've seen, MEVI should be worth it, especially in a boosted car. Plus like deezo said, if your doing a lot runs from a stop, the low end loss might help you out get better launches.

S

 

why not buy it and turn up the boost

 

Why not actually *USE* the turbo?

10, even 15 psi, aint **** for a T3/T4. Once you max out the turbo, THEN spend more money.

Why waste MORE money, when you haven't even maximized the power you've already paid for?

SC...yes.
Turbo...NO!

 

I agree...just throwing stuff on and hoping for decent gains isn't the way to do it IMO...each setup is different, maximaize gains of the present setup before throwing stuff on and being dissapointed if the gains aren't the same on your car. Corey whats up with the boost controller?? and did you clock it yet?

 

More boost cost money. I know he has lower compression pistons, does he have bigger injecters?

 

why not get more out of the high revs with a MEVI no matter what psi your at?

 

yep got bigger injectors. Addae havent had a chance to check the boost controller nor clock the turbo. I will do both Sat.

To be honest with you the reason i am not over 5 psi is because we think there is a problem with my wastegate or boost controller. My only reason for trying to decide on mevi or not is because i'm about to send my usim manifold to be chromed. But if i am going to get an mevi there is no reason to send the usim to the chromer!

 

let me know if you want me to come through

 

Well have you thought of eventually getting an MEVI after you made the most out of your current mods? If so, maybe holding off would be a good idea. If not, then go ahead an chrome the USIM.

S

 

It seems like the MEVI not only provides loads of power at the topend and may make it easier to launch, but it also smooths out the hp curve across the entire RPM range. I'm guessing this would make it easier to tune maybe?

 

More? The MEVI can't match what an extra 2-3psi will give you from 3000rpm to redline.

Once he reaches a point where he's overspinning the turbo and causing the efficiency to drop off, he can either A)swap turbos or B)leave the psi alone and look for other improvements.

It's a WASTE of money unless you're an SC to not up the boost until either your turbo runs out of breath or your engine/fuel system can't support it.

 

A *click*click*click* of the boost controller is all he needs to do.

I'd rather spend $500 on bigger injectors for 5, 10, 15 more psi, then the MEVI.

 

I am not sure that I agree that upping the boost will elminate the need for the MEVI. ( until you run out of eff. range )

Would you mind explaining it 1 more time for me?

It would "seem" to me that you would gain WHP. I know at the expense of TQ below 5000 RPM, but for what we "do", I would think the TQ loss would be helpful during launches. So running 1st-4th gear I would "think" the WHP gain would be worth while.

And with the USIM not "breathing" well above 5500 rpm, would'nt shoving more air down it's throat mean MORE HP loss?

And while it may seem I am arguing, I am trying to get my learn on. SO help a trailer hommie out.

And here is a pic of one of my last dyno's with the MEVI. One line is working mevi, one is not.



So there is a "similar" comparison.

 

Ice you have a point and I have heard your point from many of the turbo guys and was really leaning your way in the argument. but look at that curve!!!!! at 6 grand he is making at least 15 more horse power!! and this looks like its a dyno of about 5 psi. Baggs whats psi are you at on this dyno? if he was at 10 to 15 psi the multiplier effect would be killer! or should be. Also baggs can you post a the torque curve of this same run I would like to see those numbers too.

 

You cant compare an unopened MEVI to a USIM when looking at dynos. Who's to say that the results wouldn't be totally different with a USIM??

 

IIRC 6 PSI

and "peak" whp was ~20 difference


But add 3 PSI and you could make up that ~20 HP, IF the manifold is not choking itself out

BTW I was letting off due to fear of the fuel cut..lol

Here is the TQ, now the TQ "should" have been the same until 5k, it is not. This could be due to heat or any number of reasons.

However, it's about a ~20 lb difference. But it is a smoother curve.

AUTO BTW




BTW I have my USIM on now. I'll have the MEVI on after I get the car running .... but I'll have somemore dyno's to compare with.

And Icy I am not saying your wrong, I may end up with the USIM. I'm just waiting to do a little more R&D

 

Your correct. That's why I stated it.

However, here is a NA dyno of a USIM vs MEVI..

there is about ~5 HP difference until 5200... Results WILL be different using a Turbo, but they will be close. And this was just a comparison. I am looking for either nigel's dyno or hal's when they switched to a MEVI

 

Ok Bags...I'm not saying "eliminate the need", I'm just saying there are more gains to be FREE'd by turning up the BC then slapping on a MEVI at this point. MEVI will give gains, but from everything I've read, turbo guys focus on getting MAXIMUM BOOST before they worry about porting the head, porting the TB, or changing the intake manifold. Those are LAST to do and will DEFINITELY sacrifice torque to shift the power curve to the right.

Look at it this way...all the MEVI over the USIM does is reduce intake restriction at higher RPM...ignoring the low rpm torque loss for now. The reduction in intake restriction after switchover, say 5100rpm, by adding a MEVI means the turbo doesn't have to spin as fast to "force" as much air into the manifold to reach the boost controller limit. So, the USIM turbo car must spin the turbo faster to produce the *SAME* boost and *SAME* power as the MEVI turbo car AFTER the switchover, ie 5100rpm. However, if we know the turbo can *EASILY* handle 20+psi before even worrying about a drop in efficiency, then we can simply over come the reduction in air flow from the USIM restriction, by cranking up the boost controller limit to compensate...which is FREE!!! One example is the drop in pressure from an intercooler...say 2psi. On a SC car that's a concern, because you can't change boost since you're limited by peak boost at redline or in a couple Maxs'(Mardi, StephenMax) case even SC impeller speed. So, you don't want to use too large of an intercooler or you'll end up actually LOSING power from the pressure drop, since the cooler charge air doesn't equal the power lost from the pressure drop. For a turbo car at say 15psi, you can simply shoe-horn in the biggest IC you can fit, since if you get say a 5psi drop in pressure(so engine only 'sees' 10psi), you simply ADD 5psi to the boost controller limit setting and your engine still sees a chilled 15psi. Just, think of the USIM as a "drop in pressure" like the IC and how you can simply compensate by whatever that drop is with the boost controller.

Yes, you would assuming the SAME boost pressure, but I'm suggesting he turn up the boost. You can get a EBC that varies boost according to what gear you're in.

There is a limit at which your turbo can't "force" any more air, however I'm pretty sure we're no where near that.

Bags...I'm *DEFINITELY* not arguing. I *LOVE* these kind of discussions and ideas, because it makes me, you, others think about **** we've never even thought about before. AGAIN, I'm happier then a puppy with two peters talking about turbos, manifolds, naaawz, whatever car ****. Please don't think I'm 'heated' or anything. I'm definitely not. Plus, it makes work fly.

I'm not sure what to make of that.

 

Exactly what bags said, bump the boost up 3psi, 4psi, Xpsi and then you're getting 30, 40, XX horsepower and who knows how much additional torque.

Think if the MEVI adds 15whp from say 5100rpm, depending on your type/size turbo, you could be making XXwhp/XXwtq as soon as you reach FULL BOOST, ie 2800-3000rpm for a T3/T4. That's 2000+rpm sooner then the MEVI will and *THAT* is midrange power you can REALLY use during "everyday" races to *JUMP* on someone.

 

I agree with that. Makes MUCHO sense to me. Thanks for explaining it. I don't understand why I missed that in the 1st post


Thank you again. Talking to me like I am a 2 y/o.. I understand finally

Makes sense

I'll go there in a second..lol

Get back to work..lol.. You'll see where I am heading in a second

Hmm.. like why did I post it? Or that graph makes no sense?


One more second......... making a NEW thread

 

ok I have the avc-r boost controller so u\I can up the boost based on rpms so hmmm

 

DAAAYMN! You must have been one SMART azz 2yr. old.



I'm about outty.

Brain is fried...out of computing power....no more analyzing today.

 

but the true question in raising the PSI is lets say you tune perfectly with your fuel and timing, how much manifold pressure should our cars handle? Especially with Lowered Compression.

 

Redmax, did you ever drive your car with the lowered compression without boost?? I want to know cause mine doesnt seem as slow as I would have thought, and i dropped 1.5 points in compression.

 

Someone told me rule of thumb is a 4 percent decrease or increase in hp with 1 point of compression.

 

that would =
200hp at 10:1
208hp at 11:1

i would think the percentage would be more than that

i bet its closer to 12% per 1 piont compression

200hp at 10:1
224hp at 11:1

this is just a guess

 

yes more.. not in comparing the two but basically reshaping your torque curve.. making the top end stronger (vs without the mevi) at any psi. If you had idential turbo setups, 1 mevi, 1 us spec compared side by side, the mevi would pull in the top end (equal drivers). i'm not saying don't pump up the boost, just that the mevi makes the top stronger at any psi

 

Oops, I was not sure last night, but I checked again it is 8%.

200 whp would be making en extra 16 hp, man with 12:1:1 you would be making 32 extra hp.

 

28whp at the same PSI aint no joke! Add another 500rpm and it should be closer to 35-40whp

 

Until someone does a MEVI vs. USIM comparison dyno overlays like ^^ don't necessarily show the true differences. Who's to say an unopened MEVI is more restrictive up top than a USIM??

 

your correct. But when you have examples, you show them.

And it's possible to be less restrictive due to it not being sealed 100%

 

WTF, this aint rocket science!

 

Yes, for a SC car it makes PERFECT sense.

However, if your engine/fuel system can handle the extra 35-40whp at redline, you might as well crank up the boost and have it from 3000rpm or whatever rpm you hit full boost until redline.

All for FREE vs. $500+ for MEVI.

 

A 10psi MEVI car would get pwned by a 15psi USIM car while spending $500+ on a MEVI setup.

Once you hit the point of negative returns on the USIM, then go MEVI or use more drastic measures like porting/polishing.

Honestly, until you have a built motor, I *DOUBT* you'll need to worry about having a MEVI. If you already have a MEVI from your SC or NA days, then run it since you already have it. I'm just saying that if you don't already have a MEVI and you're only pushing 10-12psi with your T3/T4 or larger, you might as well just bump up the boost vs. spending MORE on a MEVI. Just my opinion though.