Best spent money on an L6

[Roady]

Well this is definately a "can of worm" topics - not in a bad way but there will be a thousand and one different ressponses and reasons why this is better than that.

There are already many good ideas on here so I am most likely just adding to the confusion.

 

That said my two cents - purely talking about the L6 engine and personal experience and dollars spent.

 

Firstly - exactly as Dat2kman stated, its one thing to buy power another if you want insurance to go with it.

Also as mentioned previously in other forums here that using a dyno can prove next to useless when comparing one car to another unless done on the same dyno same day same time etc etc.  After each upgrade I went back to the same dyno at the same time of year (winter) and observed the results - again taken with a grain of salt

 

 

My starting point was a standard L28 (F54 block) N42 head - all standard.

Dished pistons

Electronic dizzy

Extractors

Twin Hitachi SU's

 

I used this engine as an experiment to see what improvements came with what upgrade.

 

First mod was to install a 72 degree cam.  This was a re-grind (cheaper option and I know many don't approve).  Whenever you go down this road (changing cams) you also need to consider stiffer springs, new rockers, new lash pads (thicker in the case of a re-grind which you need to measure carefully). 

Total cost for all this = $1400 approx (parts only not including installation which I did myself)

Power gain = 20hp at the wheels

 

Installed tripple webers (45's)

Cost = $2500 (not including tuning +$200-500 depending upon who you get and how good they are)

Power gain = 25hp

 

Again take the power figures with a grain of salt as mentioned previously.

 

Currently going through another engine build which cost has been approx. $7000 (again not including putting the thing together). 

 

Porting work cost = $1600 (this time including installation of new springs valves etc)

Prepping the block, including boring, lightening the flywheel etc = $1600

You still need to add on cost of new valves, gaskets, pistons etc.

 

Then if you have done the work to the top end, your insurance for the bottom end involves doweling flywheel and crankshaft, sorting out a better "key" for harmonic balancer and another couple of nice to haves...

 

If I were looking at cheapest options from a complete standard L6 I would look at extractors (which you may be able to get a good semi-racing set for $900), electronic dizzy $250 approx, throw in another $1000 would get you close to the camshaft or alternatively flat top pistons).  After that I would be looking at the carbies etc, but again others will have different ideas probably better.

 

Anyway things to think about.

 

If you are talking other parts of the car and as a project as a whole - I worked on the Z's strengths first then its weaknesses last.

Its very light weight, therefore braking and handling are a good starting point.  Upgrading the brakes to prevent the fade they suffer - you can get away with a 4 runner front, R31 back set up for about $2300.

 

Handling wise - many many suspension options out there, frontt you can get away with some cheaper parts for <$200 to adjust camber anyway and toe can be adjusted already (within limits)

Rear, bit more expensive but again for <$3000 you could have your Z handling and braking significantly better than standard road cars.

 

Drive line - similar to Dave 1600, I have headed down the S15 - 6 speed option but have yet to install, nice tight ratios.  I cannot weld therefore pricewise went up straight away, you will be looking at $700-1500 to get it all cut and welded.  One quote was between $3000-4000.  Another $950 if you get the countershaft mod done from a company in SA (which I am heading down at the moment, as when I stripped my S15 gearbox the countershaft had already suffered minor damage and I am a fan of doing things once so I dont have to deal with them again).  That said, provided your S15 box is ok to start with, unless you put more than 250hp through it you wouldnt need to deal with this.

 

Subaru 4.44 LSD is my choice for a diff - but there are several subaru options out there, down side is you need additional parts doing this.  There are plenty nissan and other diff options out there if you look on this site you will find many ideas floating around.

 

Hope all this helps

[Roady]

P.S. Picked my suby diff up for $500.  Just have to be patient and find someone who wants to sell NOW

[Cozza]

720 front diff

I picked up a 4.625 for $250 I think

I'm pretty sure some models had a 4.44 or maybe it was a 4.375

 

Mick

[gav240z]

Thanks Roady very useful post, if I build my ghetto L-GATA I plan to document mods and then eventually dyno to see results. Provided my rebuild doesn't blow up on me first .

[Riceburner]

I got my Nissan R180 4.37 for $50 (+$160 for isotropic finishing)   To date it's the best mod I have done, the acceleration is fantastic!

 

1K won't get you enough head work so my vote for would be for..

1. Electronic ignition

2. 72 degree regrind, my wade 76 was $120.

3. SM or SR needles for SU's

 

 

[G]

I should probably add at this point that I have a 3.9 Subaru LSD and I'm currently putting together the pieces for a 3-3.1L stroker, so my decisions are largely already made.

 

As a result, the question wasn't asked for me per se. I was just hoping to illicit more detail (and perhaps more spirited debate) than the standard "power is found in the head" comments which although valid, don't consider the cost involved, which I would suggest is a key limiting factor in most of our decision making. Additionally, it doesn't consider the validity and impact of head modification which knocks on to fuel delivery, spark, exhaust etc. Further, it also doesn't consider the detail. If power is found in the head, is it found in the valves or reprofiling the intake/exhaust - per $ spent?

 

Case in point? I was talking to Les Collins the other day who suggested that a streetable L31 with triple 45's and a P90 producing about 280hp actually doesn't need much head work because the 45's aren't large enough for head anyway. In this regard, power would actually be found in a combination of fuel delivery and the head.

 

 

[gav240z]

Case in point? I was talking to Les Collins the other day who suggested that a streetable L31 with triple 45's and a P90 producing about 280hp actually doesn't need much head work because the 45's aren't large enough for head anyway. In this regard, power would actually be found in a combination of fuel delivery and the head.

 

280HP in a car as light as the 240z is plenty!

 

I've been guilty of watching this over and over...

 

The guy who built it sent me details in a word document on his build. He was very open about what was done etc.. It's running an E31 head from memory that had a bit of work done to it by Sunbelt in the US I believe. I might try and dig it up again.

 

Edit here is the link to the doc...

https://docs.google.com/document/d/16zH5ipj2PeoAWWO5xynZO2ywUQHn3XvHErCLgRAQg1o/edit?usp=sharing

 

~260HP at the wheels. Not sure on dyno etc..

 

Also you may or may not have seen this thread?

http://performanceforums.com/forums/showthread.php?67272732-L28-Datto-head-had-to-share!

 

But looks like several of our members have seen it already, he quotes around 10K to build a similar spec L28. Obviously ancillaries will be additional costs etc..

 

 

[dat2kman]

You chasing a P90?

[G]

Nope. I already have two.

I'm hoping to breed them.

[JIM71Z]

FREE HORSEPOWER  well almost

Now i've got your attention.

What ever happened to tuning what you have.

It is only about 1 in 20 cars that come on the dyno that is tuned correctly. Want cheap horsepower, do all your filters, put in some new plugs/points etc. Check your timing. Get yourself a rocker cover gasket and check tappets and cam timing.

The car will now generally go better and be more economical. If your car still isn't running correctly or you can't carry out this work yourself, book it into a dyno tuning shop that has experience with your chosen induction.

A full tuneup as listed should come in under $1000, depending on time spent, and will maximize what you have.

A bad modification on the other hand can make an engine perform poorly and be untunable.  eg my mates race car has a 3' exhaust. Must be good on my std engine. Wrong

On the other hand, heat shielding and cold air always work. Have seen 10+hp on 180HP engines

Hope this helps

James

[evolutionise]

$1000 : second hand set of 40mm triples

$2500 : second hand set of 40mm triples extractors/exhaust and 280zx elec ignition

$5000 : second hand set of 40mm triples extractors/exhaust , 280zx elec ignition, lumpy cam and port match, shave head for more compression.

 

Are the rough prices above include labor?

[oldmates260z]

FREE HORSEPOWER  well almost

Now i've got your attention.

What ever happened to tuning what you have.

It is only about 1 in 20 cars that come on the dyno that is tuned correctly. Want cheap horsepower, do all your filters, put in some new plugs/points etc. Check your timing. Get yourself a rocker cover gasket and check tappets and cam timing.

The car will now generally go better and be more economical. If your car still isn't running correctly or you can't carry out this work yourself, book it into a dyno tuning shop that has experience with your chosen induction.

A full tuneup as listed should come in under $1000, depending on time spent, and will maximize what you have.

A bad modification on the other hand can make an engine perform poorly and be untunable.  eg my mates race car has a 3' exhaust. Must be good on my std engine. Wrong

On the other hand, heat shielding and cold air always work. Have seen 10+hp on 180HP engines

Hope this helps

James

 

Do you think that a Dyno tune will give a marked improvement for one that has had the L28, N54 block, P42 head, lumpy cam, electronic ignition and twin SU's?

 

Mine is tuned well and had the motor rebuilt 2 years ago. It just does not seem to pull well and uses a heap of fuel to do it.

[44014]

Are the rough prices above include labor?

 

I wouldn't let anyone else work on my car.

All of that stuff is fairly basic to install and set up minus the dyno tune.