Rebuilding a B6 for Boost

[bark]

Hi,

I am currently rebuilding a B6 engine to house my Greddy Td05 turbo kit.

I have a couple of questions which I am hoping some of you can assist me with. Keep in mind I will be running it on 14-15 psi everyday but would like it to handle up to 20 psi (when required). I have a set of B6T rods and pistons that will be going in.

1) Is there any point in getting any head work done, or is the standard head quite good for flow?

2) Regarding gaskets etc, I will be purchasing a full gasket kit. Now is there any difference in a B6 and a B6T gasket kit?

3) Is it worthwhile to purchase a thicker than std head gasket?

4) Is there anything else I should be looking at whilst everything is apart?

Thanks,
Ben

[sabretooth]

1) There's a benefit, but I personally didn't go that route with my BP head. Someone who's had it done is probably better commenting, but I personally would save the headwork for if I was going for NA power.

2) Composite headgasket for the B6, triple layer steel for the BP. Theoretically, there should be no difference between the B6 and B6T. You'd want to call Mazda and ask them if the HG is composite or steel. ACL no doubt would make a headgasket also - and a triple layer steel one at that.

3) If you're going to use B6T pistons then you're going to have 7.8:1 compression. B6 will net you 9.4:1. Depends on how thick, and what pistons, I suppose...

4) Just make sure the bores are in good nick.

I'm most of the way through an engine rebuild, myself. Wiseco 8.8:1 forged pistons, B6T rods and lots of machining. I'll finally be able to resume that...

[rjr666]

ive got the same turbo set up as you am running td0518g thing.

my engine mods consist of...

wiseco 8.4CR forged pistons
B6T Rods shot peened.
Commetic MLS headgasket .040\"
Crank balanced and linished
ARP studs/bolts throughout
head slightly ported
all standard vavle springs and retainers and hydo lifters.
mazdaspeed oil pump


with a tial 38mm wastegate, and a 10psi spring it made 143rwkw. map sensor reading was 9.2psi

with just done over 700kms now, im about to up the boost to 15-18psi and get it re-tunned.

considering i rev the motor hard always up near the rev limiter 7200 cause sometimes 3rd gear just isnt possible and 2nd is on the limiter, im looking at getting anouther head and having it fully done with solid lifters and heavy duty valve springs, titanium raitainers. and full port and polish flowing the bowls, oversize valves. but till then, just going to save more money and workout if its really neccery.


imo the standard head will do fine.

[4sfed5]

1)the 1600 isnt a great flower and spending lots on head work aint gonna make it much better...plenty of people running 15 psi on engines that have done 150,000+ kms STOCK.

2)no idea.

3)not if your running low comp pistons.stock head gasket is fine as long as you keep it tuned well and it doesnt knock.(again see #1)

the only thing i consider compulsory at that boost/HP level would be some B6T rods as these are the weakest link....
if it were me id fit the head with some new guides and seals.use a stock gasket kit with some b6T rods and if youre feeling rich fit some wiseco pistons to replace the b6t's you have.......im not a big fan of the B6T pistons as they are such low compression, they make the car feel dead when not boosting.....also youll need more PSI to make the same HP as a \"high\" compression engine using the stock pistons.

OR YOU COULD JUST BUY A NB 1800 ENGINE WHICH HAS BETTER HEAD FLOW STOCK THAN A FLOWED 1600 HEAD. but thats just me

[The Pupat]

ARP studs/bolts throughout

What everyone else said but also think about using top of the line ARP studs and bolts. A lot of the time engine failure comes from studs and bolts letting go rather than actual part failure so it would be a reasonablely good idea if you've already got it in pieces.

[4sfed5]

yeah...RJR's setup is about as much as youd want to spend on a 1600..good cost/benefit ratio with a mix of stock and aftermarket parts only where required.

[bark]

All, thanks for the valuable feedback!

Over the next 2-3 months the engine should come together - then it will be a matter of choosing an ECU...

I can't wait to get this in and get on the road.

[sharaleo]

Hey bark, good luck with the build! Here's my 2c...

1) Not sure about the head configuration, but I would tend to also agree that for a forced induction application, the money could definitely be spent better elsewhere. I'm sure an efficient turbo will be able easily compensate for any meager flow improvements a bit of porting could offer.

2) Later B6 DOHC 16v (mid to late 90's) may also have been fitted from the factory with a laminated steel head gasket like the BP's, from memory, but it's been a while. Whilst in a lot of turbo applications there is often no discernable difference in the appearance of a forced vs normalliy aspirated HG, they may very well differ in actual construction and composition (and hence genuine/aftermarket part number). Forced inductions HG's must cope with much higher cobustion pressures and temps.

It important to remember that there are several variants of the B6's, so ensure you specify as close as you can to the actual build date when ordering it, otherwise I can guarantee it will be wrong (or bits of it, anyway). If I was building an engine and designing it for high boost, I would certainly do my best to find a HG suited for that app, even if I was forced to purchase it separately to the full gasket set.

3) Don't worry about a thicker gasket! These are pointless for this application and generally designed for applications where excess material has been removed from the head or block during any machining processes, or where pistons protrude from the block at TDC (as in many diesels and very high compression race applications). Highly boosted turbo cars built around thick HG's, head shims or decompression plates are just asking for trouble IMHO. There is no compensation for lower compression pistons, especially when you have the thing apart anyway

Also, most ACL gasket sets for later model south east asian or european vehicles will have been imported and repackaged by ACL from manufactureres such as Payen and Ajusa, it is just not cost effective for them to manufacture them. This can actually be a very good thing as a lot of the time they can be far more complete than ACL sets! I'd try and locate an Ajusa set, personally, as i was always impressed at the completeness of their sets. I also used to have one of their gasket catalogues, and it was by far and away the best catalogue of any vendor I had ever used (seven years in that industry). Companies such as Veale Auto Parts over here in WA can help you out with Ajusa.

4) I'll happily be the eighth or so person to mention ARP studs and bolts, definitely a good investment!

Lower compression pistons are of course a must (compared to NA). Exaclty what compression you choose is the question, and will probably be determined by your budget. Either you grab the B6T pistons and suffer the relatively poor off-boost performance, or you fork out the bucks for the alternatives that offer you a better choice, Wiseco, etc. Also make sure the pistons you choose are matched to your rods, or alternatively, make sure you get rods to suit whatever pistons you decide upon. This is important as most turbo engines will also use shorter rods in order to maintain or increase crown thickness on the turbo piston. If you use unmatched pistons and rods, you may not achieve your target compression ratio.

Also, if you are having the block and/or head faced (and you definitely should at leaast have the head faced), make sure you know what type of HG you have decided on, as it technically should effect the finish that the reconditioner decides upon (ie a different finish is required for composite vs steel HG's). Of course it is equally important that you find a reconditioner that knows this and will machine it correctly, as many don't/won't!

While you have the engine apart, also consider ancilliaries such as the water pump, timing belt and tensioners, harmonic balancer, etc. It's easier to replace these now, rather than later!

Cheers!

[Sean]

I can understand wanting stronger parts, but I see no issue with keeping the 9.5:1 compression ratio.

With a good tune and thermal managment it's quite managable to run 20psi on 9.4:1.

Remeber the car will not be making 20spi everytime it gets dríven...

For a street application, or if you plan to drive it in teh twisties, keep teh higher compression IMHO.

[bark]

Thanks everyone for your comments.

I have a set of B6T pistons as well as std NA pistons which I will match to a set of B6T rods. I am undecided on whether to use the B6T or NA pistons, I know that the NA pistons will give me more grunt down low but what is their longevity - I guess this depends on how hard I will drive it... I would assume that I would only be giving it an occassional squirt on 20psi with the majority of driving to be done on say 14psi (and that is when the car is able to spool up to that given speed limits of 60kph). What are people's thoughts and experience?