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top half runner length ~ 12.75 inches bottom half runner length ~15 inches runner from intake manifold to engine ~1.88 inches 1.75 inch runner width I took this photo just so we know how much space we have to work with on these manifolds interior shot
I was looking to buy this type of mod from a member here that built his own. VERY high level of craftsmanship. But after testing we found that it only made power above 3K so you would need a new torque converter.
I will try and find pictures and post (c32/55 forum).
I was looking to buy this type of mod from a member here that built his own. VERY high level of craftsmanship. But after testing we found that it only made power above 3K so you would need a new torque converter.
I will try and find pictures and post (c32/55 forum).
I only have a dyno of my 4.3L but the difference between the two is amazing. also the only problem i saw he had was hitting a tq limit on the tcu . If thats representative of what kind of power i will make then i cant wait to finish with this project.
If im not mistaken, to match speedybenz's intake the whole bottom half of the intake manifold would have to be gutted correct? As of right now im still working out what length i want the runners to be, then Ill order 8 stacks with the bellmouth and have a friend weld them in. Hardest part is biting the bullet and settling on a runner length.
I love the looks of swedepats design but those runners look awfully short while on speedybenz's design the runners are much longer (or it seems to be from what i measured on my intake) giving us that low-end tq we all want. DEFINITELY not going to attempt to make my own stacks/bellmouths soo hopefully mine looks as nice as swede's
****, why is this so hard? I want to tune for the 3rd wave at rpm 3500 and my intake duration is 221 degrees but somehow I get seven different answers?
Engine Pro - Intake Port Length is 24.15 inches
Simplified Chryser Formula - Intake Length is 24.00 inches
Simplified Chryser Formula 2 - Intake Length is 22.94 inches
Simplified Formula - Intake Length is 22.63 inches
Simplified Formula 2 - Intake Length is 27.97 inches
Simplified Formula 3 - Intake Length is 26.40 inches
velocityofsound.com - Intake length is 31.87 inches
Can anyone chime in and help me out with this please?
Ideally you'd want to try a few and see what works best. So many other variables at play that formulas will only get you close at best. And that isn't factoring in power preference, you can be safe in assuming that shorter will equal more HP, pending if the rest of your engine can support it and rev that high, and longer will shift the powerband lower. There isn't going to be any magic number that is best at everything, it's all give and take. You can look at aftermarket intakes for common domestic platform and there are wide ranges of versions (lengths) depending on displacement, head/cam potential, and desired powerband. If you are eliminating the dual runner length setup you're really going to lose somewhere, either bottom or top depending how long you go. Interesting project though, curious of the results.
Ideally you'd want to try a few and see what works best. So many other variables at play that formulas will only get you close at best. If you are eliminating the dual runner length setup you're really going to lose somewhere, either bottom or top depending how long you go. Interesting project though, curious of the results.
Ideally id prefer low end power for street/track racing. Maybe if i lived in Germany id go for the top end. And I know from the dyno my peak power is at 3500 so why not tune for that? I hope the top end loss isnt too much since im adding a bellmouth for better airflow and im gonna try to port and polish the intake
One concern I'd have with tuning for a lower peak RPM, your engine will really struggle to reach the 6,000 RPM shift point and there is no good way to change that. If you're way out of your power range in the 5k-6k rpm you're going to lose a ton after the initial hit. Fine for driving around but any time you run out a gear it'd be painful.
Only one way to know for sure though.
The intakes switch length in that 3500-3800 range. Unplug the vacuum line or the switchover valve sometime and go rip on it and see just how bad it falls off up top.
One concern I'd have with tuning for a lower peak RPM, your engine will really struggle to reach the 6,000 RPM shift point and there is no good way to change that. If you're way out of your power range in the 5k-6k rpm you're going to lose a ton after the initial hit. Fine for driving around but any time you run out a gear it'd be painful.
Only one way to know for sure though.
The intakes switch length in that 3500-3800 range. Unplug the vacuum line or the switchover valve sometime and go rip on it and see just how bad it falls off up top.
Im learning as im going, what would you recommend?
Took some time to read the C32/C55 thread. Some very interesting ideas and possible solutions, but also some problem areas which could crop up with the TCU regulating and cutting out torque. Looks like electronics will rear up its ugly head later down the line.
Im learning as im going, what would you recommend?
I think going from a dual length runner to a single length is going to be a losing battle in all around performance no matter which way you slice it. I'm not saying don't do it, I think it's a cool experiment and learning experience but keep your stock intake ready to put back on when you want good broad power again.
It's like taking a variable cam motor and making them fixed, you're going to lose.
If it were me and I really wanted to improve performance of the intake I would keep it dual runner but try to improve on it while keeping that aspect. Like I said you could make some improvement in certain ranges but the trade-off would far out weigh whatever benefit you are getting.. especially in these cars how we really can't control or change the shift maps of the trans. Just my .02 I do encourage you though I think that's neat tinkering there I just have no desire to spend my time doing it, 15 years ago sure.
I think going from a dual length runner to a single length is going to be a losing battle in all around performance no matter which way you slice it. I'm not saying don't do it, I think it's a cool experiment and learning experience but keep your stock intake ready to put back on when you want good broad power again.
It's like taking a variable cam motor and making them fixed, you're going to lose.
If it were me and I really wanted to improve performance of the intake I would keep it dual runner but try to improve on it while keeping that aspect. Like I said you could make some improvement in certain ranges but the trade-off would far out weigh whatever benefit you are getting.. especially in these cars how we really can't control or change the shift maps of the trans. Just my .02 I do encourage you though I think that's neat tinkering there I just have no desire to spend my time doing it, 15 years ago sure.
I went ripping around an industrial park yesterday and the aceleration made me feel like i was back in my c220 again, but when i shifted the gears manually it wasnt so bad. If I can get the length right maybe a speedshift swap will be my next project to mitigate the lost top end power . I agree though, its a fun project and with the hopes of gaining 50 hp i couldn't say no but im definitely keeping my stock intake manifold in case i need it. on the bright side i know what formula I want to use and its giving me a runner length of 31 inches to tune for 3500 rpm. do you think thats too long though? Im wondering if my acceleration will be like that in the industrial park. If the SLS did the same thing im trying to do now it cant be that bad right?
I went ripping around an industrial park yesterday and the aceleration made me feel like i was back in my c220 again, but when i shifted the gears manually it wasnt so bad. If I can get the length right maybe a speedshift swap will be my next project to mitigate the lost top end power . I agree though, its a fun project and with the hopes of gaining 50 hp i couldn't say no but im definitely keeping my stock intake manifold in case i need it. on the bright side i know what formula I want to use and its giving me a runner length of 31 inches to tune for 3500 rpm. do you think thats too long though? Im wondering if my acceleration will be like that in the industrial park. If the SLS did the same thing im trying to do now it cant be that bad right?
Speedshift swap? Are you talking about tiptronic? If so I don't see that helping anything or manually shifting your current car. At wot the car is going to shift at the maximum RPM, you cannot make it shift sooner with either shifter setup, you can delay shifts only but you can't make it shift earlier. So when you floor it, it will always shift around 6,000. Until you can change that, I'd suggest trying to work with that in mind or else you'll slow down ( at least in terms of all out performance, for daily driving this is not necessity but it is always advantageous to have shift points that work with your powerband)
And if you're targeting 3500 as your peak RPM, no way you're gaining 50 hp... or any peak HP. You might gain power at that rpm over stock, but you won't gain anything peak if your new peak is at 3500, will never happen. You can't make your 43 produce 350 hp at 3500 rpm, it just isn't going to happen. You won't be able to make it produce 302 HP at 3500. I'm sure you can improve it at any given rpm, but not what you seem to be thinking. That is a drastic change to aim for 3500 when the whole rest of the motor is designed for 6000 RPM. The cams, heads etc. I talked earlier of matching things, if you plan this drastic change by only changing one thing you can bet that the whole setup is going to end up very inefficient. The intake is not the only part that determines your powerband. The cams and heads are the real heart if the motor.
I can't help you with runner length, outside my expertise. But like I said, experimentation will be the only way to find out. I wouldn't be trusting any program enough other than to get you in the ballpark. An SLS is absolutely nothing like a c43, nothing. An engine is all about everything matching together and working together, Mercedes is the biggest and most advanced Auto maker, millions and billions into r&d on this stuff along with close to 150 years experience, I'm just saying don't expect anything based off an SLS! You can't put a unimog tire on your car and expect to go offroading
Don't take any of this as discouraging, I'm really just talking here.
Look at your torque curve. You can see where the runners change at 3800 or so clear as day. You can see on the long runner curve, your torque is peaking right around 3500 as it is. Maybe you can gain a little with the bell openings but that is about the length you want for that rpm. And you can start to see where the curve starts to drop like a rock right before the runner change, if you have a single length you can just imagine how that would completely fall off with just s couple hundred more rpm. In the higher gears you might not even be able to reach a shift point.
It's what I was talking earlier about the benefit of the dual length runners. No single length will beat it for all around power and wide usable powerband.
Look at your torque curve. You can see where the runners change at 3800 or so clear as day. You can see on the long runner curve, your torque is peaking right around 3500 as it is. Maybe you can gain a little with the bell openings but that is about the length you want for that rpm. And you can start to see where the curve starts to drop like a rock right before the runner change, if you have a single length you can just imagine how that would completely fall off with just s couple hundred more rpm. In the higher gears you might not even be able to reach a shift point.
It's what I was talking earlier about the benefit of the dual length runners. No single length will beat it for all around power and wide usable powerband.
I really appreciate your feedback, i finally got the last measurement i needed to finish this all off. So the new plan is to use swedepats method of making a new top end because I like how it looks and he has dyno results to back it up. Where he ****ed up is he increased the size of throttle body past what the maf could handle, from what I can see.
The measurements im going to use are
1.875 inches from the intake runner to the head
and 3.5 inches from the head to the valve.
overall from the valve to the bell-mouth end id like a length of 15.5 inches to give me a sweet spot of between 5200 and 5300 rpm. Sounds a little more balanced right?
10.125 inches is going to be the length of the runner+bellmouth combo im going to make. All thats left now is to order the parts and get it put together.
08-07-2017, 10:07 AM
