I'm having my downpipe made soon and I'm highly considering doing a hood exit set up. Mainly for space issues, but I also sort of like the look and sound. I'm looking for input from people who have this set up, or have ran this set up before. What are the pro's and con's? Other than the obvious, more attention, rain water, etc.

I will not be daily driving this car, more of a weekend warrior/track car.

I'd like to see pictures of your set ups as well.

 

Coverred many times

Biggest con in my opinion is that it makes tuning difficult, the length being to short for optimal sensor placement, and it scavenges fresh air in skewing the numbers.

The fact that rain / rocks and haters dropping things into the pipe doesnt sounds like a very good time either. Theres always room for a bumper dumper

 

3.25" from turbine to radiator lol - and my tuner seems to prefer hood dump set ups.

 

Still only going to be 3.25" if you go up aswell, doesnt make it any easier. If you were to go up with the downpipe, where is the dumptube going to go?

Do you not like your shiny new wastegate and turbo? because hanging them off of that chingchang manifold is certainly going to drop them on the highway

 

You won't have enough room. you can't get a flange and a bend in that short of a distance. the typical 4 bolt turbine flange is at least 1/2" thick, add in that most 90 degree bends follow a 6" or so radius (so at least 3" from the short leg end to the outside of the long leg after the bend) and you won't have enough space. you could probably get away with a cheater cut, cutting the pipe somewhere in the middle of the bend but this can cause a flow restriction and turbulence within the downpipe/turbine housing resulting in slow response, increased backpressure, increased EGTs and a loss in power.

not to mention you couldn't run a dumptube if you did go hood exit. you'd have to flip the wastegate 180 and figure out how to route the dumptube in the drivers side of the motor while keeping it away entirely from the compressor cover, compressor inlet/outlet, and the intercooler piping.

I have no idea why you have so little room, it's more than likely the eBay turbo manifold and the fact that it was designed around a ford 5 bolt turbine exit and you are running a 4 bolt.

you might have to either move the radiator over, angle it towards the passengers side (passenger side of the core moves back so you can move the radiator further over to the right), get a smaller radiator to tuck under the core support (rywire, chase bays, speedfactory, or a scirocco radiator, etc), or get a 5 boot turbine housing, or get a different turbo manifold.

the prolen with a hood exit is that it's loud, you'll cover your white car from hood to trunk with carbon and soot (worse when it rains), debris can fall in the up pipe while parked, stopped in traffic, or while driving... or someone can be a dick and put something down it (it has happened) leading to turbine wheel damage and likely turbo destruction.

also air fuel ratios will be skewed like mentioned above due to reversion sucking in fresh air, rain isn't too big of an issue as long as you aren't stuck in a downpour... you'll have to cover or plug the up pipe if not in a garage. if enough water enters the up pipe it can cause the turbine housing and wheel to rust, it could potentially enter the CHRA thru the turbine seal and completely destroy the turbo.

Also you'll never pass emissions.. there isn't enough room for a cat to pass the sniffer test. also the cat would be so close to everything that it could damage the paint and be a fire hazard... catalytic converters can easily reach temperatures of over 1600F which would cook anything near it.

also it's illegal in most states to have the exhaust exit in front of the passenger compartment/front wheels.

also cops will do nothing but pull you over left and right. there's no way to be quiet with 2ft of exhaust exiting the hood.

so basically it won't work and isn't a good idea. you need to reconsider your setup and either change radiators, get the correct turbine housing, or the right choice which is get a different turbo manifold. even with a 5 bolt you won't have that much more room...

you're stuck.

 

Chingchang manifold is going to be fine until I decide to change it, I am making supporting brackets for the manifold and the turbo for extra assurance. I appreciate the concern, but please stay on topic.

Here is a diagram of how I would have it set up

 

I don't have to worry about emissions here in Illinois (pre 1996). Anyways, my buddy is mocking me up a hood exit downpipe as we speak at his place, so we'll see what he comes up with. He had a few ideas he was tossing around to make it run in between the trans and radiator then out the hood. I am currently looking for other manifold options, and might settle with a cast log.

 

Unless you live in a county with no emissions then every vehicle under 25 years old must be emissioned. for you it means a sniffer test on the rolling road.

 

And recirculated wastegates kill power. we did a dyno test on a turbo gsr between open dump and recirculated. open dump picked up almost 30hp with no tuning.

the sharp angle that the wastegate is joining the up pipe at will make it even worse. air doesn't like to turn, much less make a 90 degree turn against another body of fast moving air. to do it right the wastegate dump needs to have a gradual merge into the up pipe at a very shallow angle like a merge collector.

I understand wanting to get it done but there's getting it done and getting it done right.

 

Okay so this is new info to me and I didn't know it had negative effects like this. Leaning toward not using this set up again and back toward the bumper dump I originally wanted. Where I live does not require ANY sort of emissions testing on pre 1996 vehicles though, so I have 0 worry about anything of the sort.

This is why I post in here, just searching doesn't always yield the best information for certain set ups.

Thank you for the constructive posts.

 

I've seen more than one a$$hole randomly drop a rock in a hood dump exit while someone stopped the car long enough to get a drink at a car meet. Destroyed the turbo in seconds. Over $1K down the drain, just trying to be cool and "different". In another instance it was a piece of ICE. By the time the damage was done, the hard ice had destroyed 3 blades in the turbine, but you couldn't tell because the ice had melted by then.

Not to mention, annoying, has a tendency to discolor the OEM windshield if placed incorrectly, and IMHO creates as much unneeded attention as it would the attention you want.

Even the wastegate ONLY as a hood exit would be better to deal with than the whole exhaust system.

Honestly, keep the open hood exit exhausts at the drag strip.

 

Yea I was considering a hood exit until I realized the domestic loving, cousin marrying, Japanese hating country folk around here would glady throw **** into the up pipe. of course I'd have to kill said person if they did that lol

 

Its a shame we cant just live together and respect peoples things..

 

In nc emissions is only tested for 96 and up. 95 and older is safety inspection only.

 

I didn't read the entire debate, but here's my 2 cents:

There are no real pros, however most of the track cars you see them on are purely due to the fact that they can't fit a large enough diameter downpipe. In your case, fitment may be an issue either way looking at the clearance to the radiator. I would also consider flipping the wastegate (if possible) to face the other direction if you do go the hood dump route. With the amount of space you have, the hood dump would most likely be in the way of any sort of wastegate dump tube. I do like the sound and appearance hood dumps and they are a lot quieter in car than an open downpipe underneath the car. I have never heard of tuning being an issue with the wideband being atleast 6" from the turbine outlet, however, anything is possible as most widebands have a recommended bung placement of ~18" from the turbo i believe.

However, you WILL have people screw with you if you don't cover the dump every time you park the car somewhere. I'd recommend covering it every time you park whether its windy, rainy, or absolutely perfect outside. Your windshield will definitely get soot on it over time and your hood will be discolored. If you live in an area where you have cool nights, I hope you have heat to run your defroster because it will also fog up your windshield.

That being said, I would still run a hood dump personally because I don't mind the inconveniences. In all honesty, however, it is not practical for use on a car that sees the street a lot. The bumper dump would be much more practical, however, it is quite a bit of work to do right. If I recall correctly, it should have a flex section and have a solid support somewhere on the outlet side of the flex section, so the engine has space to move without the pipe murdering your bumper.

 

I didn't even think of the fogging of the windshield, I have no blower motor or vents. I am going with a bumper dumper anyway. I appreciate everyones input. Friend of mine is helping me make the downpipe, he's finishing it up tonight or tomorrow mid day, dyno target date is Saturday.

 

The wouldn't be American lol.

the one thing I don't like about living in Ga in the metro area is every car that isn't 25 years old has to be emissioned, I'm glad we don't have safety inspections because my civic would never pass being literally half an inch off the ground and running a huge tire stretch, 240 wouldn't pass either lol.

Having to swap my civic back to OBD2 for the scan test sucks... and I'm afraid when I get my big motor in it that the stock ecu won't be able to idle GSC T1s without throwing a code. swapping cams would suck.

there are counties outside the metro area that don't have any emissions at all but it's the middle of nowhere with scary mountain folk lol.

 

^ Why not get a P.O Box in a state or somewhere else where emissions is not required and register your vehicle there?

 

I enjoy my hood exit but its basically a track only car. no staining on the hood, no issues yet with the windshield. Its quieter in the car. Absolutly no tuning issues or data logging A/F when making passes. The issue with the sensor being closer to the outlet of the turbo is the sensors wont last as long but still read perfectly fine. A nerf football works great for plugging the pipe up fyi if you go this route. Or you could clap screen on there and not have to worry about plugging the hole

 

I think you'll find mountain folk quite personable once you get to know 'em.

 

Would it be too hard to move the rad over some ? All the fab for the downpipe seems harder

 

You can't use a po box.. and you have to have proof of residency in said county. drivers license, power bill, etc.

not to mention those counties are fairly far away and I would have to get my tag from the tag office in that county.

 

Or a fellow member could help you out lol

 

I just remembered that the house we are supposed to be moving into in August is in the next countt north of us and it's 100% emissions exempt.

win win because swapping wiring harnesses, ecus, different sensors, injectors, camshafts, and every other thing associated with stock parts and OBD2 compliance is a bitch.