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Advice on Lag

Hello to all addicts of performance upgrades and weeties!
My Dilemma!!!!
Ive heard conflicting answers in the past regarding Turbo Lag and how to solve it
Anyone who has experience in this area id be happy to hear from you,

My car Car is a 1977 930 3 litre
The engine without intercooler, (i do not know the history of the engine it has 210000kays on it and runs quite nicely, the numbers match so i know the engine is the one that left factory

The dash guage boost bar reads to 1.5
the Turbo in it has been replaced for a recondition one about twelve months ago with a kkk turbocharger, according to reciepts, thats all i know, i dont know if the exhaust etc is stock and to be honest i dont know if the turbo is a porsche model either, as i bought this car without premium because of the gaps in history

But i do know the Lag can be annoying and its not in the best interest of my quiet area to drive on the edge of boost all the time in order to keep it ready if needed...

So im suffering the long spool up until it gets up to speed, but then there is no complaint.

What would be a good fairly quick (inexpensive??) way while maintaining reliability to reduce the lag?
If there is no inexpensive way then does anyone know the next best way?
Im willing to spend a bit of money on it and more if the modification guarantees a good improvement.

ive added a couple of photos of exhaust and turbo to help with ideas

Any thoughts?






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Old 05-29-2013, 05:37 PM
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Not to be a wise butt.......there is tons of infor here on this board.
I still will recomend you buy Corky Bell turbo charger book. lots of good info!
Lag is it or threshold ? LOL
Or is it boost leak
others will jump in here too I am sure
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Old 05-29-2013, 06:01 PM
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Brando
 
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Sell me your car and go find a sorted 3.3.
Most everything about the 77 3.0 turbo points to lag. And you really want to keep it stock these days anyway with the value going the way it is these days. Or at least keep all the parts to bring it back to stock configuration.
I have the same basic engine but mine is so warmed over it wouldn't resemble yours especially in performance. There really is a lot to do. I'd start with a small k27 first I guess. Then exhaust and then cams. Then intercooling and then comes..........you get the idea. The slope gets steep. Good luck
Old 05-29-2013, 07:10 PM
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Put the smallest turbo possible on it to reduce lag.
You'll never get rid of the turbo lag on a '76 or '77 930 since it has low compression ratio on par with a flathead lawnmower
Old 05-29-2013, 07:18 PM
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Brando
 
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Mine has .8 bar by 3100 rpm stock compression.
But I have headers, diverter valve, sc cams, gt30r turbo low restriction muffler, etc.
Old 05-29-2013, 07:37 PM
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We added our headers to a stock '77, no other changes, and reduced lag 1000rpm and added 100HP. If you do nothing else, slap a free flowing muffler like ours on it for a 300rpm lag reduction.




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Old 05-29-2013, 07:49 PM
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Quote:
Originally Posted by JFairman View Post
Put the smallest turbo possible on it to reduce lag.
You'll never get rid of the turbo lag on a '76 or '77 930 since it has low compression ratio on par with a flathead lawnmower
Thats a false statement, ask Frank about the turbo lag on my old 77...

if you add headers and a gt30 you'll eliminate most of your lag, time your distributor for 32 degrees max advance and you'll have a very smooth drivable car around town. I have found that the 3.0 liter motors are much more responsive then the 3.3's with a few mods.
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Old 05-30-2013, 05:34 AM
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pkracer21j is correct. The 3.0L can be very responsive. The lack of intercooler means less volume in the intake system.

The thermal reactors are a big problem. Very restrictive. Muffler is also a restriction source. I do not recommend the Rarly headers, but definitely either headers, or the later 1986 on stock system if on a budget. They turn up in the classifieds here.

GT30 is also a good turbo choice. You might be good already though, since we don't know what turbo you have. I personally don't recommend over 28 degrees total timing, but definitely set for more advance.
Old 05-30-2013, 07:22 AM
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I've heard the compression ratio on the 3 liter 95mm bore '76 and '77 930 is 6.5:1, is that correct or is that just the '76?

The 97mm bore 3.3 used from '78 through '93 is still low compression but at least it's 7:1 and thats a little better for a street motor. It's also got a little longer stroke crank and that's going to give a little more torque at low rpms where you have the most turbo lag than a motor with lower compression and shorter stroke that's also 300cc's smaller... especially while running stock CIS injection.

The 3.0 has 2mm smaller bore and shorter stroke than the 3.3 and that gives lower mean piston speed and piston distance traveled per crank revoloution. Because of that shorter stroke slinging the weight of the piston back and forth it rev's freer at high rpm's and makes for a better track motor.

A smaller ball bearing Garret turbo (like your GT30) spins up a lot faster than the usual journal bearing 3k 3ldz or K27 turbo's most people run on these cars and that alone will reduce turbo lag better than anything else you do.

Raise compression up around 8:1 to 8.5:1 and run lower boost to compensate for that while using street gas and that will reduce turbo lag and give alot more low speed torque and pep for an all around more drivable street car if thats where you want to go.
Install SC cams with cam timing advanced as far as possible also helps lower range rpm power.

Advancing the ignition timing curve quite a bit from idle up to around 3200 rpms to get away from the stock EPA emission control oriented timing helps too and doesn't cost anything if you do it yourself,,, like you said.
Old 05-30-2013, 08:19 AM
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Quote:
Originally Posted by Speedy Squirrel View Post
pkracer21j I do not recommend the Rarly headers
Because ...?
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Old 05-30-2013, 03:24 PM
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Good directions thx,
Some of my confusion is re adding an intercooler, i did enquire at a Porsche place about adding one to help reduce lag,
he said,

QUOTE; if you add an intercooler it will only increase lag as there is a larger volume of air travelling through it, there's not much you can do to reduce lag; ENDQUOTE, wtf?

So this is NOT true?? This is why i needed to ask here directly and i appreciate it,

The Headers sound good to me ill ring up muffler shop today and see what they can do as i do have some holes in the muffler anyway from low driveways scraping,

Internal engine work will have to be on the cards in future too as i dont know whats inside etc,
but i have prev owned a 76 Euro carrera 3, which was very light with similar performance figures (on paper) but it would never hold a candle to acceleration this car has, i have a suspicion theres been work done as the whole area between where you sit and the stuff up front is made of PLYWOOD !, or is this normal?

So i think with all changes anyway it would be cheaper to modify it how i like rather than taking it back to factory as some turkey put a cab roof on it anyway and 11k to fix that is not my idea on money well spent as i dont see the outside of the car when im driving anyway...

But INTERCOOLER, ??? can i put a 3.3 intercooler on it? remember its a 3.0, is it as simple as that?

When i bought it about two months ago i saw her and thought yep for the price im gonna restore it to factory original and make $$$$ profit (i paid $24k) but now well.. i just want more POWER, im addicted..

Good or bad who cares but when driving porkers i think many may agree there's not many things in life that feel as good
Old 05-30-2013, 03:41 PM
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I just wrote a long post thanking but turned out i wasnt logged in DAM!

i was told this by porsche mechanic

Quote ; if you add intercooler it will increase lag and not reduce it as theres more air travelling through it, theres not much you can do to them to reduce lag. ;Endquote, wtf??

next and sorry for sounding abrupdt but im pissed that ive got to write this again!
i will get headers sounds good starting point...
engine work has to be on the cards soon as i dont know history and whats inside so i will need to at least need security of knowing that.

Must be work done in body at least as the wall between where you sit and through to bonnet is made of plywood go figure, or is that normal?

i used to have a 77 carrera 3, on paper similar performance but if im to compare the two driving it wouldnt hold a candle to my second and third gear acceleration is as fast as first (feels like it)

Sorry starting to brag in the wrong place , my d#c%ks bigger than yours , but why not we're allowed to as im older now i dont get much fun at home unless im in the shed feeling (working) her (the car) lol

ok Today headers tomorrow who knows, but intercooler !!???
PORSCHE mechanic guy is wrong???
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Old 05-30-2013, 03:53 PM
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OK
i thought the first post didnt post !!

its early sorry about that
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Old 05-30-2013, 03:54 PM
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Intercooler will not help in one respect, but it will cool which actually makes power and thats debatable but I believe it's true. I know when I simply put on an intercooler on my 77 3.0 turbo the difference was that it made it feel less smoothly transitioned. It would boost with a snap rather than a smooth build up of boost. but it was quicker overall which means more power. Then you can add boost and legitimately make more power safely.
You can add an intercooler two ways. One is to get the factory intercooler add on system the dealer sold which consist of some adapters for the intercooler from the factory to fit the non cooler engine physically.
The way I chose is the 964 elbow with diverter valve in Lu of the factory diverter lump you currently have. Just remove all that crap and replace it. Makes the engine so much nicer to look at and work on not to mention the fact it's better. Then choose your intercooler that fits the longneck style and install. Done.
Add that and a k27 unit and you'll make good power, If you swap the headers you'll do it quicker.
I'd sell it for a profit and buy a 3.3 with goodies already installed.
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Last edited by quattrorunner; 05-30-2013 at 11:01 PM.. Reason: Spell
Old 05-30-2013, 04:28 PM
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Thanks all,
Update , short term ive invested in a Monty muffler, in hindsight glad i did as the old one was a mish mash of two different exhausts i think, god knows,
see other thread on the crap i found under the bumper,
Sometimes ignorance is bliss,

thx all for the excellent advice and views,
Rob
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Old 06-07-2013, 05:05 AM
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I doubt the monty will assist but hope so. It's a baffle muffler so flow is challanged.

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Old 06-07-2013, 12:56 PM
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