Hi everyone! i've got a 1978 mercedes C107 chassis 450slc drift car ive been building, i have a small vintage mercedes parts business and boneyard with about 30 1960-90 mercedes. So i have the parts to build the car for next to nothing at this point. I'm an equipment mechanic and been messing with all manner of cars, as long as they are rear wheel drive, for 30 years or so. fabrication is not an issue for me.
The car is a four speed manual conversion with a welded 3.69 diff. I've done some suspension work and have it working pretty good, still need some nice coilovers to really dial it in though. problem is anything over 55 or so and third gear it just doesnt have the stones to keep tires burning. This is my first event with the car video, end of the straight (when i didnt miss a shift) it was at redline in second so it was ok, but its like 55-60 at 6100 rpm.

The engine is a stock 4.5 ltr m117 mercedes v8 with fully mechanical bosch k-jetronic Constant Injection System (or CIS as many know it). lots of european cars used it from 74 up to the 90's, including the monster and last to use it, porsche 911(930) turbo. If you have 20 min to kill here's the gist of how it works.
The stock engine is rated at 180hp @4750rpm and 220ft/lbs @3000 with 8-1 compression, so its no power house. these cars were cruisers mostly. I've bought the fuel system control pressure regulator or Warm Up Regulator(WUR) its really mistakenly called, from a porsche 930 turbo which is boost referenced to enrich under boost. This should keep the air fuel in check as the fuel distributors of the porsche and my car are very similar in standard pressure settings. Its adjustable to a degree also and can be modified to be easily adjusted. If i have fuel issues i'll cross that bridge when i get to it, but low boost under 12 i should be fine.
I've done quite a bit of research and talked to some knowledgeable people but i've come to realize that even the best advice can include mistakes and just wrong numbers sometimes. so its best to get alot of opinions and use your best judgement and really look at how many people tell you similar or the same thing. If 10 smart guys tell me something in the same ball park ill believe it more than one or two guys that are way off what of the others say.
So I would like to hear what the people on this forum have to say and any advice you all can give. Ive had turbo cars and had them apart and stuff but never built a custom system. I've used some calculators including "another calculator" on here and my numbers seem pretty close to each other and my guestimations. i"ll put my chart up and a map from a holset hx30 thats too small.
I'm aiming for 330-350 at 8 psi or so to be safe and get the ball rolling. It currently falls on its face at about 6100 rpm but its capable of 6700 in the shorter stroke version, im guessing it runs out of head and cam. its getting the cams from the high revving motor and the boost should fix the small valve problem. 8-1 compression isn't helping NA but is just fine for boost. Its got a forged crank and rods but cast pistons (im pretty sure about thee pistons) so i'm thinking like 400 ish at 10 psi once tuned properly is about the limit with stock pistons. I'm thinking about the ebay t70
https://www.ebay.com/itm/T70-T04Z-T...05&rk=1&rkt=1&&_trksid=p2045573.c100505.m3226
with t3 turbine housing. My local guy who has been building bad ass turbo everything since the early 70's says go small on the turbine side and work up. I'm going to have him balance and check the cheapy turbo out.
Compressor Size:
* Trim: 75
* Inducer Diameter: 56.6 mm
* Exducer Diameter: 75 mm
* A/R: 0.7

Turbine Size:
* Exhaust (Turbo Manifold) Flange: Standard T3 Flange
* Exhaust (Downpipe) Flange: V Band Flange
* Trim: 78
* Inducer Diameter: 74.4 mm
* Exducer Diameter: 58.4 mm
* A/R: 0.82
So at this point i need advice on the turbo like, are these ebay t70 or gt35 or similar actually clones of anything i can use a larger exhaust housing or wheels from? Do you have a better suggestion for a turbo? Ive had hx35 reccomended and looked at the hx40 maps which look better to me but i dont know about housing and wheel replacement parts. how about intercooler and piping? I think 2.5 should be ok for my power goals but can i go 3" without losing some throttle response? being a drift car low end isnt real important but throttle response shouldn't be really bad or its not gonna work so well. its always gonna be 3500+ and really more like 4500 to 6500 most of the time. how big of an intercooler should i be looking at? Radiator is going in the rear if space becomes an issue.
These cars have massive fuel flow capabilities and the slightly newer than my car 560sl roadsters have twin high flow pumps I'll be running. I've seen guys using these pumps on turbo ls builds so i know i'm good there.
There's a couple vids on my channel of the car and you can really see the lack of power on the faster portions of the in car at summit point(plus it was only my second run around the track). hope my long winded intro didnt run anyone off. Thanks for getting through all this if you have and i look forward to everyone's input.

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Have you looked at matchbot? I would think something around an S300 62/68 would work pretty well.

 

Matchbot? Never heard of it. Also haven't heard of a s300. I'm
Looking mostly at stuff under 300-350$ so if that precision or something pricy it's out. When you say 62/68 is that model or one wheel or big
Or small side of both wheels?

PS. The motor is 92 bore 85 stroke

 

http://www.turbos.bwauto.com/aftermarket/matchbot.aspx
It takes a little messing with to get used to, but there are tutorials available for it.
62/68 refers to compressor/turbine size, Inducer on the compressor and exducer on the turbine. I am sure there is a good fit china turbo, i'm not sure which one it would be though.

 

https://www.amazon.com/dp/B01DNV5L0G/
ok. I was looking at this guy last night before i dragged myself to bed. that fits the bill pretty good, right around the 60 area my local guy recomended starting at on the turbine side. a little larger than the china t70 i was considering. plus its water cooled. any opinions on bad or good there? is it going to put heat in my cooling system i dont want? So many aren't watercooled is it really necessary? And its Maxpeedingrods so it has to be good! ;-)

 

I think you will want a t4 foot if you're looking for 400+hp

 

i'm thinking 400 is as far as i want to go on stock pistons. Its more than double stock power, although the euro spec 9-1 make about 230. im ok with it falling off at 6500 or so. i want it on full boost by low 4000's. I need to keep the throttle response decent too.

 

You definitely want a T4 not a T3. If you are making 200 hp you'll need around 15 psi to make 400hp. There's also the 69mm gt45 turbo too

 

I don't want it to spool lazy and i spoke to a very long time turbo guru in my area who recommended a t3 to start with and about a 60mm exducer turbine wheel. It may keep me from over revving the shit out of it too65-6700 is all want to go with it. I have another project with a smaller 6 cyl if this is actually to small. As far as needing 14.7 psi to double horsepower, isn't that true for a highly efficient, tuned engine? This engine is low compression and a pretty small cam and valves. Boost should have a greater effect on a low power to cu in engine than it would on a high power NA engine. look at a 4.8 ls based engine. it makes almost 300 na. if you put 14.7 psi through it your going to make a hell of a lot more than 400HP because it flows way better than my 4.5 NA. A small amount of boost will make up for the low compression and small cam then a little more should have it up in the 350 400 range. The calculators ive used all have been fairly close to each other and have me 330-370 at 8 psi and 350-390 at 10psi at 6000rpm. stock hp is 180hp with 8-1 compression.

here's at zero boost and 4750rpm and 78%ve where my engine peaks according to specs, 203 at the crank would be lower with manufacturer ratings. 180 would be about right from 203. torque is dead on.
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these two are at 8 and 10 psi at only 78%VE.
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14.7 psi
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I can't say the calculators are spot on but it makes sense that a bad flowing engine will respond to boost more than a good flowing one.

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A single T3 just isnt going to cut it... even on a small engine you would cap at 300hp. I would be looking at T3 if you had half the displacement and half as much NA hp... maybe. Best case scenario the engine just wont rev because it cant exhaust what it needs too. Worst case you overdrive the turbo and blow it up. Your going to have a miserable time gating a too small turbo, its going to generate way more compressor heat than a properly sized or oversized snail would. Even spraying methanol pre compressor to make it act larger is not going to help on the exhaust side. Plus, when you discover the t3 really is too small your then going to have to rebuild your hot side with a different flange and rebuild your down pipe. If you dont believe me just google T3 max HP.

You need a T4, period. You are already talking about spinning this thing to 6500+ and even if you keep it to 6k, you really don't need to be making boost until 4k, a smaller t4 is going to get you in way earlier than that. If you want to see some successful builds that are around this size look at the first generation mustang 4.6l, similar displacement slightly more NA HP, look at their turbo selections then make a decision.

https://www.ebay.com/itm/Rev9-TX-66...ash=item25ccbf8892:g:NV8AAOSwYwJaBNTj&vxp=mtr That is a 66/70 t4. Should be almost perfect for your application, and seems to be at the right price point. I believe these are turbonetics knock offs.

 

Very valid point. I'm so anti ford from my early years the early tird 4.6 never popped in my head for comparison. That makes total sense. They are very similar in output when compression is the same. Thanks for giving me an example I could wrap my head around. I'm wondering now if my local was a little toasty the night I spoke with him and mixed up some numbers. I was thinking that Exauhst all coming out of a 2.25 exit was gonna be tight. I haven't had The chance to check that turbo out too much yet,is that a common China turbo?

 

Yah, there are a bunch of them on eBay and Amazon

 

I'll have to poke around on that a little after work.

I did throw another wrench in it today though. I have a way smaller momo wheel on the car and it basically blocks my view of the tachometer at a glance. When I'm drifting it's definitely no time to look at the tach anyway so I pretty much shift it by ear or when it falls on its face. I decided to get a video of where it falls on its face and where it drops to at the second third gear shift today,and was shocked by the 7100 RPMs on the tack! I've measured my speed against a gps and found my tach reads 300 fast so more like 6800. Still way higher than I thought it was spinning. Looks like it drops to About 45-4700 into third so boost by 4000 should be fine. I'm going to do a tune up on the car and have it dynoed on a hub dyno with a wideband later this week I hope. so I'll be able to see what it's actually doing before I change anything. I have to say I'm impressed I've been winging it that high and it hasn't had any issues besides pushing some oil into the catch tank. Like not even half a quart after an all day event, probably 30-35 drift runs. I need to check my cam codes and scope the Pistons to see if it's actually the low compression original motor or not while I'm changing plugs for the dyno. Can't upload right now for some reason.

 

Thats a lot of revs. Hopefully some others will give you an opinion.

 

Yeah I've always wondered if the cams were stock us spec crap but never was ready to change them so it didn't really matter what they were. Now I'm super curious. It really is still pulling hard up to there too. I don't know if it's got fuel or spark cut or if its floating valves or just out of breath. But it definitely hits some wall and it's all done.

 

Wall could be valve float. A turbo will probably give you another 1000 rpm of usable range. If your valvetrain and rods can handle it.

 

Yeah. AMG lightened the cam followers or rockers(not really on overhead cams) and I'll probably do that too. Rods are forged and are known to be pretty bullet proof. I've never actually come across a blown up m117 that wasn't run out of oil or tossed a timing chain from bad guides.

I added the video of the run up to 7 grand to that post.

 

No one ever blew up a Mercedes because the only people that drive them are driven by 65 year old people lol. The old Mercedes are good quality cars idk what happened to them now but the cars for the US markets are total junk. The company admitted to build the cars to only last 5 years. There maintainence schedule promotes the early demise of your car so you buy a new one. I work on so many Sprinters it's ridiculous with under 60k on the clock that need a lot of repairs. I'll stick with Fords and Chevys anyday

 

You should keep your hot side small like 2"-2.25" piping to help with response. Ball bearing turbos help in a little quicker spool too. I'm sure you can find around a 62mm T4 to fit your needs.For your downpipe use the x 1.25 rule for sizing it so your not creating too much back pressure