N9T Heads that dont crack?

[White]

Hey all, I've recently picked up a '91 SW8 that will be getting a turbo manual swap in the next year or two. Im a big Volvo guy and really like the looks of the N9T on paper. Ive read a few threads about people building them up with Volvo pistons and Saab rods, they're closed deck, the port shapes in the heads are nice too. This is freakin awesome. But it appears as if they all have issues with the heads cracking... I LOVE making good power on unusual engines and keeping the original drivetrains in cars. But head cracking, to me, is a dead end. I'm not going to build an engine thats going to crack heads, I will swap a better engine in at that point. My question is, it appears as if Politecnic once made heads for these cars? Do these have the same cracking issues? Is the cracking due to a poor design or due to poor castings? 

Really excited to made this amazing breadbox fast! I appreciate any help!

[Bean]

Welcome to the forum White!

Sadly the Dani heads can crack as well - lots of thoughts on this, but I personally think it’s poor cooling system design that isn’t capable of self bleeding air out of the system.  This to me is an issue as the head can develop air pockets which can cause massive temp differentials in the head. Redoing it so the head self bleeds (steam tubes like they do on an Ls) with the reservoir the highest point, as well as a swirl pot in the system to ensure an air free system is my plan.  (I have a new Politecnic/ Danielson head)
 

The one universal however is I’ve never ever heard of a professionally repaired head fail again.  Last I read Erickson still fixed heads for $1100usd or so - which to me isn’t very much at all all things considered.

Definitely on the same page as you with wanting to make great horsepower on original engines and drivetrains - they key for me would be using modern standalone ecu’s handling fuel, boost, and ignition.  With modern control and turbo tech on these engines I think they could be pretty darn impressive

Rabin

[Jayden M]

Similar to what Bean said the performance heads like the Danielson head supposedly does not solve the cracking issue, however the heads usually only crack when its overheated. The issue is that it doesn't take much overheating to get the heads to crack compared to other engines. 

I can't confirm this as I am still working toward this goal (fairly recently restored the car), but supposedly a 505 Turbo stock will pull up to 155 mph, which I'd say is a solid base for a car from the 80's.

I too have another 505 turbo I want to build up to put out some power so I'm curious to see where this ends up.

[White]

2 hours ago, Bean said:

The one universal however is I’ve never ever heard of a professionally repaired head fail again.  Last I read Erickson still fixed heads for $1100usd or so - which to me isn’t very much at all all things considered.

Ahhhh okay thats interesting, thats really good to know! I'm gonna have to look into steam tubes and do some research. I'll be using a Haltech when I do the swap so it will be a nicely controlled setup! Its too bad nobody has found a good 16v head that will line up yet. I wonder if any of the major companies that makes headgaskets have a data list they could search.

[SRDT]

I'm not sure Politecnic had special heads castings made, Danielson was using stock heads not fully machined from the factory.

The JRD engines from the 70' had special heads and even blocks I think, the dual plugs head at least could not be stock.

[Bean]

There was a formula car that had a special DOHC head for the N9TE block, but they’re beyond rare.

My thought is this engine will never need to rival a 4G63 or a K series Honda, but they can still be made pretty damn stout with upgraded turbo and supporting systems like fuel and ignition.  My goal was 300 RWHP in a daily without being ridiculous to drive.

I currently have a EFR6758 Borg Warner turbo, ID1050x injectors, Dani head and cam, LS coils, cosmetic head gasket, ARP head studs, and an AEM Infinity 508 ecu for mine…. Now if I can ever get the time to dive in!

Rabin

[V-M]

As said above these heads are originally not designed for turbo usage and thats one reason to add to list, heat waves and knocking (even slight ones) combined to over heat are killer for this head. Good thing is at usually heads which are professionally welded repair are not so sensitive for those issues mentioned. I have passed to other users or used my self around 15-20 heads. And still have 4-5 heads on storage which are not welded (no dani heads anymore). Welding costs around 400e + machinery+valve work. I did make one dani head from normal one but that was very costly, combined price was around 1800-2000e. I have T4OE (from Group2 Lancia integrale), saab 9000 IC, Volvo pistons (B21et), Dani head  and cam, special head gasket from italy with separate seal rings (can be reused).

[White]

On 10/8/2022 at 10:29 AM, Bean said:

My goal was 300 RWHP in a daily without being ridiculous to drive.

Thats pretty much exactly what I was looking to make with one, the head cracking issue just had me worried! I did recently find out that they used the N9TE in the Citroen BX 4TC and I would love to build a replica someday. So perhaps I'll shelve my big turbo N9 ideas for now and just toss the OM606 I have lying around in the 505 hahaha. Appreciate all the responses here so far. Its very hard to find good info on these cars!

[Bean]

The OM606 would be pretty epic in a 505 wagon! What trans?

I’m a Peugeot guy and all, but a modded 606 would have all the power and be crazy efficient as well.  Get a nice hitch and it’d also pull amazing.

Rabin

[speaksgeek]

23 hours ago, Bean said:

The OM606 would be pretty epic in a 505 wagon! What trans?

I’m a Peugeot guy and all, but a modded 606 would have all the power and be crazy efficient as well.  Get a nice hitch and it’d also pull amazing.

Rabin

I wonder if the OM606 might be a bit big to comfortably fit in the bay without some surgery to the firewall and tunnel. I've seen RB26 go in, which required some intrusion to the cabin I think. I think some V8's fit, I've seen a ford windsor in a 504 for example.

[SRDT]

The Indenor diesel is ony a 4 pot but it's a huge one, if you can fit that then there is hope for one or two extra cylinders on a more compact engine.

As for V8's it should not be too much of a problem when on top of the long diesel a wide SOHC 90° V6 was fitted from the factory.

[Mike T]

On 10/7/2022 at 7:00 PM, Jayden M said:

....supposedly a 505 Turbo stock will pull up to 155 mph, which I'd say is a solid base for a car from the 80's.

I remember reading this in Peugeot-L years ago and although I can't be arsed to look up the km/h per 1K RPM info right now, I recall at the time that the gearing in 5th at redline would allow something like 135 MPH. That, combined with the considerable front area and dreadful drag coefficient of 0.41 (perhaps lowered to 0.40 with the Turbo's spoilers) makes it exceedingly unlikely that any stock 505T could make it to 155 true MPH, which is 250 km/h. With an SCd as high as that of the 505T, the engine would have to be well over 350 HP to push it that fast through the air, even if the gearing would allow it.

As a comparison, the fastest car I've driven actually at its top speed for several minutes was a Mazdaspeed 3 with ECU remap and massive custom intercooler. With a much smaller SCd - the Cd alone was 0.32 as opposed to 0.41 or 0.40 for the 505T, taller gearing in 6th and certainly more than the stock 263 HP, it would pull an honest 150 MPH but no more, even though there was considerable more room in the rev range. That was a bit disappointing, as the supposed top speed was 155 MPH in top, stock!

[V-M]

There is many power houses if looking widely from 4cyl to V6 which are easy to put 400+hp wheel and much cheaper than building it from original or with engine which needs a lot of fitting work. I would say at this current build as I have is around 300-350hp and was cheap option to build (did take time to collect and fit all). Surely needs to use some more adjustable ECU for that numbers but thats an another story (currently running it with original ECU and injectors etc).  From memory BX 4TC there was some text saying at it was measured around 400hp but I dont remember where it was sayed. Still pretty weak numbers compared to other B group cars at the time.  

[SRDT]

The BX 4TC was set for failure from the start, it was a cheap Audi Quattro wannabe made with too much off the shelf parts.

They could not use the 205 Turbo 16 powertrain, had too little money and as Citroën was all about FWD they could not even make a basic mid engine RWD car to at least fight with the R5 Turbo on tarmac.

And if, somehow, they had managed to make a car that could rob victories from the 205 how do you think Peugeot would have reacted?

[V-M]

3 hours ago, V-M said:

There is many power houses if looking widely from 4cyl to V6 which are easy to put 400+hp wheel and much cheaper than building it from original or with engine which needs a lot of fitting work. I would say at this current build as I have is around 300-350hp and was cheap option to build (did take time to collect and fit all). Surely needs to use some more adjustable ECU for that numbers but thats an another story (currently running it with original ECU and injectors etc).  From memory BX 4TC there was some text saying at it was measured around 400hp but I dont remember where it was sayed. Still pretty weak numbers compared to other B group cars at the time.  

[Jayden M]

18 hours ago, Mike T said:

I recall at the time that the gearing in 5th at redline would allow something like 135 MPH

I think automatics might have taller gearing than the manuals, as I believe with stock sized tires it allows for 169 mph. I am pretty sure I have done over 140 mph even with my car down on power. (Was riding next to a friend in a modern BMW at 140 mph and it was still climbing in speed but very slowly). If I ever get the car to run as well as it used to I will be sure to video it. I am super curious and skeptical to see what the car can really do to see if those old rumors of 155 mph are even close to true.

[Mike T]

It's aerodynamics, not gearing, that will limit the top end. Don't rely on the speedometer!

[V-M]

I bit doubt over 130 (200km/h) speeds with original suspension, in straight and wide road and good weather maybe 140. I have done 210km/h with GPS but suspension and engine is not stock. 

[White]

On 10/12/2022 at 8:47 PM, speaksgeek said:

I wonder if the OM606 might be a bit big to comfortably fit in the bay without some surgery to the firewall and tunnel. I've seen RB26 go in, which required some intrusion to the cabin I think. I think some V8's fit, I've seen a ford windsor in a 504 for example.

Hmmmm, it might be too long I havent measured. I finally picked my 505 up the other day so I should look. Anything can fit with a welder and an angle grinder though lol! Honestly I dont have terribly huge plans at the moment other than removing the auto trans ASAP and getting an N9T in there in the next year or two. Once some of my other huge projects are done ill come up with something cool for the Pooj! Either a built N9T or some weird engine nobody has done before lol.

[Bean]

I think your math might be off with the power needed Mike.  Aero has a lot to do with it, but proper gearing most definitely will help.

CD is only part of the equation, and you need to factor in frontal area before you can calculate how much drag - found this site which was neat to compare:  http://tech-racingcars.wikidot.com/aerodynamics

Not saying they’re still great by any stretch, but by todays standards they are quite small, and quite light, so I think 300HP still makes for a decently quick car (10lbs/hp)

Gearing:  More than a few manual cars hit top speeds in second highest gears (4th or 5th) because OD takes the engine out of it’s power band, and it doesn’t have enough power at that lower RPM to overcome drag in top gear, but can still accelerate in one lower.  (IE:  Did the Mazda pull redline in 5th?)

Back in the day I had my 504 v6 up to a gear limited 130MPH (calculated from rpm (6500rpm), gear ratio (3.89), trans in 4th 1:1, and tire diameter (25.7”)) - and that was a carbed 604 motor with 4sp manual.  I could do 6500rpm in 4th with that car, and it’s cd is even worse at .44. 

Just out of curious - With 3.46 final drive, .87 final drive (5th) and the same 25.7” tires - that’s a gear limited 165mph if it had enough power.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

*I didn’t vet either site for accuracy - but seems fairly legit, but take with a grain of salt.

 

 

 

 

[SRDT]

Proper gearing is needed to reach top speed but the max value is just HP vs CdA.

I can't find values for the 505 turbo but the Euro V6 has a Cx (Cd) of 0.37 and a SCx (CdA) of 0.76 m² ; top speed is 205 km/h with 170 hp. The 180 hp turbo is at 210 km/h.

The 200 hp Danielson reach 215 km/h but the SCx should not be exactly the same, they had wider tyres but also a few aero parts on the kit and maybe shorter springs.