Old school hottie build or forced induction?

[NitroDann]

Then there is the supercharger vs turbo debate.

Still?

[speed]

Then there is the supercharger vs turbo debate.

Still?

Not with me. We all know that I've been there done that.

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[speed]

I was respecting the OP's vision to do something outside of the mainstream but the reality is that there is substantial costs involved to build a N/A screamer.


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[Magpie]

If you want value for money boost.

If you want to go NA, then sell your first born and accept that you will still be slow in a straight line.

Compare my dyno graph to even a basic boosted car and mine looks very average. Do not get me wrong I like my NA build and will never part with it, but some days...
Mark MX5 by Eipeip, on Flickr

This is what you get to enjoy from about 2:15
https://www.facebook.com/mx5na6/videos/628157220905414/

[NitroDann]

Right now you have about 105rwhp.

Adding extractors and full exhaust and ecu might net 125whp.

That's $4000 on a good day.

Adding cams will cost $1000 for the cams and approx 1500 to have a shop do everything required to get them perfect.

This may net you 30rwhp at the expense of significant economy and behavioural changes.

So for $6500 you may make 150-160rwhp and it will be harder to drive, behave much worse, and chew a lot more fuel and make less low end power in exchange for more peak rpm power.

Or $9500 for 270rwhp drive in drive out. Better than stock economy and stock driveability with better than oem torque starting at 1500rpm.

To understand the value that's 7.7hp/$1000 vs 17.4hp/$1000. Doing the calculation by torque makes it a lot worse again.

Sell it and buy a cheap se.

[StanTheMan]

I do have to agree I went through a shitloads of petrol on my B6. dont expect any difference on the 1.8

[3gress]

Apart from the spirited driving quip there is no mention of tracking the car. It more sounds like you want a weekend escape (egress:wink:) device.
Nitrodann could build you something sweet, close to budget and insurable.
Then again if you want something to assualt every sensory imput to your brain and body i would go naturally agitated. Find a low km late model 10:1 stock block, fit decent cams and get some minor headwork done. Clean the ports of dags, portmatch manifolds. Sort your fuelling...nothing like a noisy walbro a couple feet from your head to remind you that the end for internal combustion engines is near, fit a decent ecu. Maybe some deshrouding work about the standard size valves and a shave for compression.
On that note, i had 0.070" (2mm, my conversion to old school inches may be lacking) and had only a little bowl work done to account for quench characteristics, something beyond my mediocre brain.
Apparantly most shops baulk at head shaves due to messing with quench, i.e. the way the combustion burn spreads evenly across compressed mixture (again mediocre brain) though i had no troubles when i first had the head shave done with power increasing considerably, no other mods to account for this.
I then went back for chamber C.C. work after noticing one exhaust port sooting up more than the others. Later attributed to a buggered injector stuck open.
Short story: CARBS, CAMS, COMPRESSION...or in injected engine terms individual throttle bodies or madjak manifold!
Can be done without going too far over budget and 160hp in a sub 1000kg car is more than enough to look forward to the weekend.

[NitroDann]

Nitrodann could build you something sweet, close to budget and insurable.

It would cost double his budget to do it full complied as a drive in drive out package. but it will still be more than double the value of doing n/a mods and not having it legal.

Dann

[3gress]

Double the horsepower too.
Usually budget-wise you should set a $ limit then triple it...so i wasn't too far off

[manga_blue]

Let's try taking a pragmatic look at what you must do to rebuild this engine first and then examine the low cost performance option.

As I understand it you've got an NB8A BP4W engine with standard inlet and exhaust manifolds and a cracked piston.

To bring this engine back to life the block will have to be stripped down, almost certainly rebored, maybe decked, new pistons fitted and it would be wise to upgrade the bearings, balance it all and get some weight sliced off the flywheel while it's all there in pieces. The head will need checking for cracks and heat damage (because cracked piston) , some shaving and you might as well get a 3 angle cut while it's out too.

Don't be tempted to do heroic head shaves. Changing pistons to high-comp ones is a far, far safer and more effective route.

After machining, gaskets, seals, bearings, belts, etc you're probably looking at around $1,500 -2,000 just to put it back on the road in condition good enough for some reasonably hard street driving, but not real racing. That's the base cost before you start any significant mods, for both hottie or turbo options. The only difference at this stage is whether you buy high-comp pistons for hottie or low-comp pistons for turbo - though the price is pretty much the same.

Done well this will be a much better engine than you could ever buy second-hand.

Whichever way you go you then need to think about a proper exhaust. Add $1,000 and get a decent custom build from a reputable builder like Nitro Dann or T&C.

Likewise you'll need a decent ECU. Browse the other ECU threads on this site. Realistically you're up for at least another $1,000 there for one which is working and properly tuned for whatever you do.

For safety I'd throw in a coolant re-route, whichever way you go, too. Add $200.

As an alternative to turbo or mad n/a builds you could now consider a low cost natural build. This would involve getting rid of the lousy NB8A manifolds. Get an NB8B exhaust manifold. Also get either an NA8 inlet manifold with an adaptor plate or an NB8B inlet manifold - there's no real difference in performance though the NB8B option is a bit simpler to fit up. Get some low-level porting done on the head and inlet manifold; match up all the ports and flow the throttle body into the manifold. . You can do this yourself with a die grinder or a dremel as long as your keep it all very modest. Just remove the dags, smooth the ports, match the mating faces, open the bowl above the valves out a fraction, etc. If you're putting in hgh-comp pistons you can take a bit of metal out from around the valves (unshrouding) but just be really, really conservative with it all. Serious port shaping needs serious skill, experience and equipment. Anyone with patience and common sense can do a reasonable modest tidy-up.

If the head work is done effectively and you decide you are happy to drive the car between 3000 and 6000rpm with the odd squirt to 7500 then you don't need to spend on cams for a street car.

That low-cost build will set you back anpther $500 max on top of the $3,700-4,200 for the basics, the exhaust and the ECU that you would need to spend whichever way you go.

At the end of the day, for $4,200-4,700 you would get a silky street motor that spins freely and safely to about 7500rpm. It will be totally tractable in traffic. Power will be up around 30% from stock to around 100rwkw but the spread should be much better than stock. That spread, combined with the ability to spin freely will make it feel like it's got a lot more power than that. It will pick up easily from below 2500. Remember a real screamer will bog at anything below about 5500.

And it will be a hoot to drive.

If that's not enough for you then just take my base cost and add as many $000s as your wallet can bear for mad hottie or turbo builds ....

[3gress]

"Heroic headshaves"?
My feelings are hurt..
But i digress, since you are looking at a bottom end rebuild high compression forged pistons are the way to go for an NA build.
Head shaves are for the ghetto modders...or to get rid of headlice!!

[NitroDann]

Ive done 2x extremely heroic headshaves on NA6s that years later still absolutely haul arse, but I know how to check that it will all work nicely.

Magna blue your prices are optimistic, and youve accounted for no labour to pull the engine then disassemble it, drive it everywhere, reassemble and reinstall it all and get it all working right.

Dann

[manga_blue]

I was costing for DIY for all that, Dann, except machining. The whole proposition becomes ridiculous when you add 20-40 hours of paid labour.

Stop calling me magna.

[NitroDann]

Sorry Manga. I pronounce it in my head right but my fingers type with autocorrect haha.

yes 20-30 hours labour makes it expensive.

[manga_blue]

Yes, it's only really possible as a side project, which he can do because he has a going engine in the car. If you set a timeframe of 12 months and you know what you're looking for you can pick up most of the components pretty cheap.

Worst comes to worst you can abandon the project and sell the head.