Post your performance mod ideas! - Page 2 - PeachParts Mercedes-Benz Forum

tosbt · #16 05-06-2004, 04:05 PM

Everybody would like to upgrade their 108/109 without engine replacement. Faster more efficent.

Tomguy · #17 05-06-2004, 09:52 PM

I definetly need more efficient - I max out at 10.5MPG and I figured "It can't get worse if I drive like a madman." - Wrong!

j9fd3s · #18 05-07-2004, 12:44 PM

well you'd get at least 3 things that would help mileage.

1. decel fuel cut, you can turn off fuel 100% on deceleration, i'm not sure if the stock ecu does this?

2. you can run it slightly leaner, although its possible that mbz/bosch already have it fairly lean in certain places

3. sequenital injection: basically if the mixture shows up at the right time, you can get the same mixture to the cylinders as before while using less fuel

also you could have a stronger more modern ignition too, and eliminate the distributor

tosbt · #19 05-07-2004, 04:42 PM

I've gone to the Crain ignition, cut my fule/air mixture to as about as lean as one could get. Still think about 12 is all i'm getting out of my 4.5. MANYA posted a real good link for conversion to electronic fuel management system and I do wish I could install such on mine but there an't no way in hell I could do it and I'll bet there an't nobody in 1000 miles near me that could do it either, that would want to. I beginning to think the early 4.5s have the same cams as the 3.5s(not sure TOMGUY) PETER is going to check in tech manuels. Driving my car today I loved every moment BUT would love to run about 275 horses in that motor. :p

Tomguy · #20 05-07-2004, 06:20 PM

I can say I'm pretty damn sure that the cams were different...

A seller I was running correspondance with a while back had told me the cams had "116-48" on one of them (and that was the extent of the part number). The auction is still on eBay but who knows for how much longer:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=34202&item=2460853007

smogged are 54/55. 4.5 are 52/53, and 3.5's are 46/47.
Sholin posted numbers a while back...

Quote:

Just looking at the cam numbers, they don't list total lift but intake/exhaust value opening and closing numbers by cam code. The M117.984 should have a code 52/53 cam in it that has the following characteristics at 2mm lift:

int open 4 deg ATDC, close 14 deg ABDC
exh open 30 deg BBDC, close 16 deg BTDC.

I think if you do the math, this works out as an intake duration of 190 deg and exh duration of 194 deg. 2mm lift is a larger than the .050" you usually measure domestic cams at, so this cam is actually larger than it seems.

The 46/47 cams show the following characteristic:

int open 8 deg ATDC, close 20 deg ABDC
exh open 21 deg BBDC, close 7 deg BTDC.

Here's a wierd one, the M117.982/983 cams, code 54/55 (which I think are from a smogged W116 450 SEL) apparently have more aggressive cams:

int open 5 deg ATDC, close 21 deg ABDC
exh open 25 deg BBDC, close 5 deg BTDC

This amounts to a cam duration of 196/200 if I've done the math right.

The 450's have a better intake range but atrocious exhaust range, that's where the power is zapped.

4.5 cams stock:
int open 4 deg ATDC, close 14 deg ABDC - 190°
exh open 30 deg BBDC, close 16 deg BTDC - 194°
The exhaust valve closes 20° before the intake opens

450 cams stock:
int open 8 deg ATDC, close 20 deg ABDC - 192°
exh open 21 deg BBDC, close 7 deg BTDC - 194°
The exhaust valve closes 15° before the intake valve opens

3.5 cams stock:
int open 5 deg ATDC, close 21 deg ABDC - 196°
exh open 25 deg BBDC, close 5 deg BTDC - 200°
The exhaust valve closes 10° before the intake valve opens

3.5's have the best intake range and a "compromise" if you will on exhaust, but provide for more power (top-end, I'd imagine, not low-end).

tosbt · #21 05-07-2004, 07:10 PM

Well TOMBOY, looks like there is hope for a power increase after all. I was begining to suspect that the early 4.5s had the same cams as the 3.5s.

Tomguy · #22 05-07-2004, 09:57 PM

Friendly response!

Yeah, there is a hope, I was going to pop around $200 for this, and I looked into it because I wouldn't spend $200 for the exact same cams I picked up a week later for $45, including admission to the junkyard on dollar parts day ($25), and a bunch of other parts (126 dizzy and ps pump, 116 ps pump identical to 4.5's, brake master cyl and booster, a handful of temp sensors, injectors and rails, and both valve covers, for only $45!)

tosbt · #23 05-08-2004, 08:00 PM

Would not respond any other way. I am still unsure if the cams can easily be swaped, but you have been very helpful and I will continue to research this subject. If I feel the cam swap can be done I intend to swap. What I really would like to know if anyone has done it before, seems to me that if it was both a real power gain and easy it would havve been done several times over.

Tomguy · #24 05-08-2004, 08:33 PM

tosbt: Gotta remember, in the US, the only 3.5's were grey market, '71 300SELs, or 3.5 coupes/convertibles - not many at all. These were probably driven to death like most 4.5's (neglect, rust, etc) and crushed. So it isn't easy to find this stuff and just do it. If I had the possibility, I'd try 3.5 heads too just for fun

tosbt · #25 05-11-2004, 07:50 AM

I have looked into this cam swap (4.5 to 3.5) and still am not sure of the benifits. What would be in YoUr opinion the Horsepower gains? I have heard suggestions that in may not be any more than 10 to 15.

It just would not be worth doing if it did not have a net gain of at the very least 20. Are all 3.5 cams the same? I'll bet not.

j9fd3s · #26 05-12-2004, 05:17 PM

on my dyno software you go from 197hp to 211 by putting the 3.5 cams into the 4.5. hp peak rpm is still 5000rpm. headers are worth another 20hp.

for what its worth the 3.5 gains 35hp just from headers.

the 3.5 revs higher thus making more power in the software.

take these numbers with a big grain of salt, as it is a software simulation that doesnt take into account things like detonation etc etc

Tomguy · #27 05-12-2004, 05:21 PM

FYI: The 4.5 is 230/279 stock. The 450 (smogged 4.5) from 76-80 w/K-jet and colder cams is ~200 (197 sounds about right)

j9fd3s · #28 05-12-2004, 05:51 PM

thats another thing theres plenty of hp ratings to choose from, i dont know what correlates best to what i'm using.

i'm 'getting' 231hp@6000rpm and 250@3500rpm for the stock* 3.5 and 205hp@5000rpm and 267lbsft @3000rpm out of the 4.5 out of the software

mike

*bore, stroke, compression, cam duration, and valve sizes are all per the shop manual. theres guessing on the intake flow, it doesnt model exhausts too well (ie tuned), head flow is also a guess, and i think cam lift; although i might have found that in the book

Tomguy · #29 05-12-2004, 05:59 PM

PaulC posted this a while ago: Just HOW fast is a 4.5?

280SEL 4.5: "This vehicle was an early 1972 rated at 230 hp @ 5,000 rpm and 279 ft. lbs. torque @ 3,200 rpm and had a New Jersey registration (not a California car)."

280SE/c 3.5: "This vehicle was an early 1971 rated at 230 hp @ 6,500 rpm and 231 ft. lbs. torque @ 4,200 rpm and had a New Jersey registration (not a California car)."

j9fd3s · #30 05-12-2004, 06:05 PM

when did the 4.5 get lower compression?