16v boxer with turbo?

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Oleino
Posts: 12
Joined: Tue Jul 07, 2020 12:10 pm

16v boxer with turbo?

Post by Oleino »

Has anyone here done a turbo conversion for a 16v boxer engine?

I did for mine couple of years ago, and back then I wasn't able to find any project threads. There were some photos and videos of 16v turbo boxers, but that didn't get me very far with thinking how should I do it and what parts should I use. I know a guy who had built a 8v Sprint turbo, and was able to steal some of his ideas.

So... If you have installed a turbo to a 16v boxer I'd be interested to hear how you did it, why you did it like that, what problems there were, and what was the purpose of the build.

I built mine for road use, and the true purpose was my interest in how stuff works. It's my first turbo build, and also my first turbo car. :D

Parts I used:
KKK K26 turbocharger from Audi 200 Turbo
Wastegate from Audi 200 Turbo
140x550x65 intercooler
Generic Bosch 044 style fuel pump
Generic pod filter
470cc Injectors from Astra sportymodel (Z20LEH engine)
Megasquirt 3
MAF sensor from 156 V6
Wasted spark coil and external ignition module
TPS from Volvo 850 (Bosch 0 280 122 001)
Remote oil filter
Innovate MTX-L+ wideband lambda

And all this on a quarter million km driven stock engine with whopping 0,4 bar boost.

Charge piping was done from 51mm exhaust pipe bends. Oil dipstick pipe and engine side support rod had to be modified to get enough room for turbo stuff. Catalyst is stock, and so is rest of the exhaust system from there. Megasquirt is attached to stock engine wiring harness with an adapter harness. There is also an additional wiring harness for the wires that I didn't have on the stock engine wiring harness.

It was surprisingly difficult to find a good selection of compressor maps. From the maps I was able to find, I figured that the turbo on Audi 200 (and some other Audi models) would fit to my setup. Sadly it had external wastegate which turned out to be quite difficult to fit in the engine bay. Now it's installed horizontally next to chassis rail and has almost total of 2cm play on full suspension travel between the tie rod and drive shaft. If I would do this again, I'd try to find a compressor map from a turbo which is used on the 1.8T VAG engines and see if it would be any good. It has internal wastegate and I expect it be technically better than the turbos from 80's. There are probably other more modern (cheap and well available) options too.

At first my intention was to use speed density algorithm for engine control (=MAP as engine load). That's what majority of car people are using with their aftermarket ECUs. Of course I had the awesome individual throttle bodies, and because of that I wasn't able to get a usable MAP signal for engine control. MAP signal was usable once the engine got on boost. When the engine was not on boost the MAP signal was close to atmospheric air pressure even on a slight throttle. In practice it was not really possible to scale the fuel map for this. The dyno operator told me it would be possible to make a blended fuel map. When not on boost, the engine load would be based on TPS, and when on boost it would be based on MAP. As you can imagine, tuning that kind of fuel map is time consuming. Especially if you have flexfuel-plans. One option would have been to gut the individual throttle bodies and install a normal throttle body. Dyno guy also told me that MAF sensors are sh*t and he wouldn't tune such car. I did some research on internet, the internet too was saying that MAF sensors are sh*t and nobody on their right mind uses MAF sensor on an aftermarket ECU.

I did the reasonable thing and started investigating how OEM manufacturers have tackled the problem. It came to my attention that Nissan had built turbo engines with individual throttle bodies (SR20 and RB26DETT). Both were equipped with MAF sensor, like many OEM engine managements are. I installed a modern hot film mass flow sensor instead the ancient flap sensor and got my engine running very well on all engine loads. I called the dyno operator and told him what I had done, and that I had driven some 200 km or so and found out it works fine. He thought about tuning a MAF car for a short time and decided it might be interesting after all.

Future plans include adding an oil cooler to the system and making air intake from some OEM air filter housing. And flexfuel and boost control.

Was it worth the trouble? Yes, I think so. It made only 151hp / 189Nm on dyno, which is not a huge increase over stock power, but still nice figure for a lightweight car. Later I found out I was missing up to 2mm lift on some camshaft lobes. After fixing that and building a new exhaust I think there is a little bit more power available. On positive side now the car makes cool whistling and choo choo noises which I didn't have before. There is also potential for increasing the power from what I have now.

Let me know if you guys have experience on 16v turbo boxers! It will be interesting to hear if you did it like I did, or in a some other way.

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KevJTD
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Location: Lincs

Re: 16v boxer with turbo?

Post by KevJTD »

A very interesting idea, I'd be keen to see some pictures of the install and to know how you overcome things.
Am I right to think you sited the turbo above the engine block?
How then did you route the exhaust to drive the turbo..
Or did you fit it near the gearbox output shaft, which would give huge heat issues to the gearbox, maybe overcome somewhat by use of an oil cooler for the gearbox but not as simple as that sounds without having electric pumps to circulate it..
I can't imagine there's enough room under or to the side of the engine/heads to mount it low down.
Also where did you route the oil supply and return?
You mentioning the alterations needed to the oil dipstick pipe so assume the turbo got mounted around that point, gravity would help the oil return back to sump from up there.

Sounds a great project even if the results might surprise some, but without lowering the compression ratio it's always going to be a limit of boost that will limit the potential power gains but I for one applaud the project 8-)

Adie Hawkins over here has done much work with turbo installations with huge power results, but at equally startling prices! Nothing good ever came cheap...


http://www.ahmotorsports.co.uk/
Giulietta JTD 170
Lancia Delta integrale
Lancia Flavia coupe 1.8 1963
Lancia Dedra turbo
Renault Clio 197 RS

I'm bad with people things
But I should have tried more

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Oleino
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Joined: Tue Jul 07, 2020 12:10 pm

Re: 16v boxer with turbo?

Post by Oleino »

You are correct, I mounted the turbo above the engine block. It's in about same location where the pipe between stock air flow meter and air filter used to be.
resize_DSC04815.jpg
I have seen some turbo installations on 8v boxers in same location, but in my case the bigger 16v heads made it more challenging. Even after changes to oil dipstick and engine side support rod the space was very limited, because the tie rod requires a lot of space. Oil filter was relocated to front RH corner behind bumper to have more space for turbo stuff. Wastegate was installed on the empty space between exhaust manifold and downpipe.
resize_DSC04621.jpg
The oil feed to turbo is from the new oil filter housing. Oil drain from turbo goes to oil pan. I was able to weld a fitting just above the splash plate. It's not as high as I would want it to be, but it seems to be working in practice.

Exhaust manifold is 4-2-1 design. Equal length 4-1 manifold would probably be better, and I have seen some photos of a Malesian (?) built 146 which had it like that. Then again I'm not building a race car, and Impreza WRX has same firing order and same design for the exhaust manifold as I have, so how bad can it be?
resize_DSC04793.jpg

Kegsti66
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Joined: Fri Sep 26, 2014 7:20 pm
Location: Northamptonshire

Re: 16v boxer with turbo?

Post by Kegsti66 »

Wow !!
That is a tight squeeze.
Welcome to the forum, and thanks for sharing your project, I wouldn't have a clue where to start.
Good luck with further plans.

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Oleino
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Joined: Tue Jul 07, 2020 12:10 pm

Re: 16v boxer with turbo?

Post by Oleino »

Thanks! I have a project thread on alfabbs.fi forum, but after finding this forum I though this would be better place to share wisdom and get hints and tips on boxer engines.

Future plans include installing engine back to car :D I did a rather unsuccessfull engine overhaul last year and managed to multiply the oil consumption. :roll: Now I have another engine from 145 which will be going to 33 at some point.

I have visited the ahmotorsports page before, but the stuff there is way too high end for me, and the price tag is what you can expect for the racing stuff. There is some very cool parts though.

bobkelso
Posts: 41
Joined: Fri Mar 20, 2015 2:59 pm
Location: Italy

Re: 16v boxer with turbo?

Post by bobkelso »

Hi Oleino,
it's nice to see such a custom project like yours

I link here the reference to another project, from Bert308,
(1800cc boxer with nissan pistons) if eventually it can be usefull to you:

viewtopic.php?f=3&t=486&start=30

It seams that slightly ovesized 89mm pistons of high quality,
low weight, low price pistons (before lockdown they where available,
at 100 euros a complete kit of 4 with pins and rings)
from relatively common Nissan engine KA24DE years 98-04
(avoiding the KA24DE years 93-98 pistons, they have a lateral skirt not optimal
for using in the boxer block, they are the ones in the photos in the discussion)
could be used in the alfa 33 boxer to build a 1800cc boxer,
if one could solve the main problem they where about 1 mm lower in deck height,
(ideally they need 1 mm longer custom rods or skimming the block 1 mm)..

..but if you are searching to lower a bit compression ratio because
you are building a turbo engine with not excessive overboost
maybe whey are just spot on to have a more usefull compression ratio?

In the discussion was examinated pistons for boxer 8v, but the nissan pistons
are available in more versions, some have also the 4 indent in the
piston head for 4 valve engine, some other are identical to alfa pistons
and can be eventually if necessary machined if valve space is not enouth

Another minor problem was finding compatible head gaskets for oversize pistons,
but people on forum using oversize pistons of 89mm on race car referred
they can use normal 1.7 head gasket (for 88mm pistons) without mechanical interference,
also if it is not optimal because giving at the gasket rings a bit more than normal exposition
to combustion heat, it works;
actually there is also another option, AHM made available as spare
their custom head gasket for oversized pistons on boxer

Last evenutal issue we know it is that maybe at more than 150CV
the "little" 33/sud gearbox could need a precise rebuild to manage them ;)

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Oleino
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Re: 16v boxer with turbo?

Post by Oleino »

Thanks bobkelso! That is some very interesting information!

Sourcing reasonably priced stock parts from other engines and using them for performance is pretty much what I have been doing so far. :D Did I get it right that the later KA24DE-IV pistons would not have the problem of piston skirt touching the stock Alfa connection rod from the opposite bank? First time I read the thread I somehow understood it would have been the problem, and was the reason why Bert308 had sourced the new connection rods.

If I got my math right, the stock 16v boxer has:

Bore: 87 mm
Stroke 72 mm
Compression ratio: 10
Engine displacement: 1712,07 cm³
Compression volume: 47,56 cm³

And with the 89mm Nissan pistons which have 1mm lower deck height (assuming there will be similar indents), the numbers would be:

Bore: 89 mm
Stroke: 72 mm
Compression ratio: 9,37
Engine displacement: 1792,69 cm³
Compression volume: 53,50 cm³

I haven't tested (at least yet) what is the boost limit for a stock engine running on 98 RON petrol, or what it is when running on E85. Maybe I will get there at some point. What I have heard from a friend of mine who heard it from another guy, is that based on the other guys experience 1,0 bar of boost was too much. I haven't met the another guy, and I have no idea what broke down and if he was using pump gas or E85 though.

Anyway for a forced induction application I think that bigger displacement and slightly lower compression ratio are both a step to right direction.

What is the first place to break down on the gear box? The spider gears or something else?

bobkelso
Posts: 41
Joined: Fri Mar 20, 2015 2:59 pm
Location: Italy

Re: 16v boxer with turbo?

Post by bobkelso »

At the moment the Oem nissan pistons so economic
(kit of four with rings and pins was at 75-100e
because used also on some 'humble' nissan pickup)
seam a bit less easy to find on-line, I think due to lockdown,
I hope they will return more available in few time,
but yes, there is a version without the lateral skirt and that have the head
really similar to the Alfa pistons 8v very (only the 1mm difference deck height):

Image

Here some :
with rings
https://www.amazon.com/NISSAN-ALTIMA-23 ... B07HYGZYN8

without rings
https://www.amazon.com/gp/offer-listing ... dition=all

Not sure if they will need or not some work to free some space for the 4 valve hollows,
and maybe compression ratio will be even a bit lower (8.5?) than expected (9)
if you consider the alfa 16v pistons seams more "full" on the head than the 8v version:

Image

About the gearbox, I'm not a real expert, hope some other will write about,

I have never had the opportunity to rebuild myself a 33 gearbox,
I only have read what other people have done:
to start with you need to rebuild it with new bearings to avoid plays
that will decrease a lot resistance, and also the weak link and clip
between the small cluch axis and the primary axes of the box need to be new,
the clip is frequently broken also on normal 33 on the road;
also planetary gears and their lateral inner bearing and pins
need to be on good shape to avoid they can be ripped of,
some 145 16v they ripped them (but 145 is an heavier car than 33)
About cluch, you can find some copper one (maybe expensive)
or one reinforced coil pressure plate (unconfortable to use),
but there is an 'alternative' mod maybe more in your style to cunstomise
piece using some time and attention, to use a normal oem 220mm clutch disk
and clutch pressure plate from opel (I have writed some where the model)
on the alfa 16v flywell that will do the job,
the flywell on alfa 16v use 200mm alfa clutch disk, but have space
for a 220mm clutch disk (surely there is this predisposition
on the alfa 145 boxer 16V flywell (also if alfa didn't use this predisposition
to fit bigger clutch disk, they just stopped to produce the boxer models )
but If I remember probably also the 33 16v flywell could be already ready
for a bigger 220mm clutch disk).
Oil should be new, with classification ExtremePressure 4 or 4.5
(probably also 5 is compatible) as alfa required
to protect the differential and pignon.

After this I have read a lists of improuvements people that race with have tried,
starting from inferior gearbox plate (aluminiun fusion) donated from 145,
but eventually using instead a more thick custom aluminium plate and better fixed
to the box ( to reduce flexibility/torsion of the box), and the reinforced rear
conic bearing for secondary axis available from AHM.

the gearbox of 16v and of last series of 33 (and of 145)
is probably the most strong of the sud/33 series,
planteary gears with inner lateral bearings and a bit more aluminiun thickeness
near the bearings, but it remains very "little" if you compare to subaru gerabox
for example, it is the weak point of the car, originally on 800kg and 100cv/hp
sud it was fine, but it was not thinked for such long evolution about heavier car
and stronger engine; so, the more recent alfa boxer gearboxs at stock
seams to manage 150cv, and with the more simple attentions above
it seams 180cv (also if probably we should talk aboyt torque more than cv
but it give an idea; the more torque on 33 I think was the rare TD engine);
over these values, probably gaerbox needs other more expensive parts
(you can see some other on AHM site) or alternatively to be prepaired
to some more frequent rebuilds, expecially if the car is raced ;)
Attachments
nissan-pistons-alfa-boxer-8v-1800cc.jpg
alfa-33-16v- piston.png

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Oleino
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Re: 16v boxer with turbo?

Post by Oleino »

I have broken one set of spider gears, so that is why I thought it would be the weak link :mrgreen: But that was probably just because in 2007 or so the younger version of myself though it would be a good idea to launch the car with clutch from traffic lights. :roll:

The Opel clutch sounds interesting. I had no idea of that upgrade at the time, so I went and got myself a new Drive Torque clutch and pressure plate from Larkspeed. https://www.larkspeed.com/shopper/i/DT4 ... Clutch-Kit
According to their customer support it should handle 40% increase in torque without problems, not to say it would be the absolute maximum limit.

I had never before driven a car with a dual friction clutch, and wasn't sure what to expect. In practice it is actually a very nice to drive. The feel is almost the same as for standard clutch - just a little bit more rpm is required for smooth take off. Pedal feels a bit heavier too, but not much.

I did some googling based on your post, and it seems that the 145/146 1.7 16v flywheel could indeed fit a larger clutch (215mm from Opel Vectra 2000), while the 33 16v flywheel can fit only 200mm clutch. Also I understood that one difference is the trigger wheel which has different angle between first tooth and cyl 1. TDC. (33 16v has a 60-2 tooth pattern and it's 90° from first tooth to cyl 1. TDC if anyone needs the information for their aftermarket ECU setups). I have a 145 1.7 16v engine going in and a 33 1.7 16v engine coming out of the car right now. I think I'll do some measuring on the flywheels and see with my own eye what differences there are.

Here is some more discussion on the clutches: https://www.alfaowner.com/threads/flywh ... ns.339178/

alfadave
Posts: 1411
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Re: 16v boxer with turbo?

Post by alfadave »

If I wanted a turbo charged stallion, I'd buy a Scooby, or a Fiat Coupe?

bobkelso
Posts: 41
Joined: Fri Mar 20, 2015 2:59 pm
Location: Italy

Re: 16v boxer with turbo?

Post by bobkelso »

Hi, I don't know if is a reliable option to lower a bit compression ratio,
but searching for engine spares I walked in these
"lowering CR" heads plates for alfa boxer engines:

http://www.alfasud-parts.co.uk/catalog/ ... 2&refprod=

I remember also on some discussion someone reporting an AHM suggestion
it was possible use pistons from 1.7 8v boxer to lower CR on a 1.7 16v turbocharged,
I imagine probably it will need more work, i.e. probably it needs mill pockets
for the valves in the external crown of the piston,
same doubt as using some types of the Nissan pistons on a 16v head

I put a link about this to another good image that was realised by Bert308,
he directly compared section of alfa 33 1.7 8v and 16v pistons:

https://www.alfaowner.com/threads/8v-pi ... 25&slide=0

User avatar
Oleino
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Re: 16v boxer with turbo?

Post by Oleino »

Good stuff!

Lowering plates feel a bit edgy, but I definitely don't have the experience to judge. I remember that some Corvette guys talked about head gaskets with (slightly) different thickness. Not sure if it's something that is available for Alfa boxers, but for the 350cid Chevrolet small block that is one option. I guess the concept would work? Of course the CR cannot be altered much that way.

I haven't been spending much time in the shed lately, so there is not much progress with 33 either. However I had the time to compare the flywheels of 33 and 145. The missing teeth are in same location and there are no problems attaching the flywheel to the crank. 145 flywheel has indeed space for bigger clutch, even though the stock clutch plate is same size as on 33.
33 flywheel
33 flywheel
145 flywheel
145 flywheel
Sorry for the orientation of the photos. I have no idea why they are like that :mrgreen:

The bolt pattern for pressure plate is different. I had to put the 33 flywheel back because I'm not replacing the clutch this time. If (when) the next time to take the engine off comes, I'll just might be prepared with a bigger clutch and change the flywheel.

If I'll be re-building the old oil burning engine one day, the Nissan pistons would be the most interesting option. More displacement and lower CR would both be a step to right direction.

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