...dead headed pressure was 55-60 psi..i turned it down to what you recommended..unfortunately i only have a cheap underhood fuel pressure guage so i have no idea what the readings are under boost.....no air/fuel ratio guage either..maybe you can explain what you mean by using the stock o2 to get that range??? ..its a blast to drive though!thx,mike.

 

No, you did not do it like a recommended. Read it again

Just add a hose to your cheap gauge and tape it to the windshield while you drive. You aren't doing a dead head test by turning down the center screw. You need to completely pinch off the return line to do that.

For the O2 sensor testing, just hook a voltmeter to it's signal wire and read it while you drive at WOT.

 

I did pinch off the FPR return line with pliers and i got a reading off 55-60psi[deadheaded reading]....i have since readjusted the BEGI top center screw to the 50psi range having the vacuum disconected....When the vacuum hose is reattached, the reading drops back to the normal factory setting[25-30psi]...ill try your suggestion of extending the guage to the wiper area so i can read the pressure under boost.....ill also look into taping into the stock o2 signal because i have a volt meter...you know,could i use the unused o2 that is located in my turbos downpipe???i believe its just a one wire o2??its just sitting back there doing nothing!??thx again,mike.

 

your deadhead reading should be in the 80 PSI range OR above 100 if you are running an FMU.

 

Okay, well you never said anything about a pliers. You made it sound like you dead headed it by cranking the onset screw. Like B4Ctom1 said, you probably should have at least 80psi with the pump dead headed. I run 80psi of fel pressure in my car at 6psi of boost at WOT and sustained load to achieve the proper AFR (measured 12.2-12.4:1 with the wide-band).

I would try tapping into the O2 sensor closest to the engine, especially if you have a converter in place yet (like I do). The O2 sensor needs to be hot to work properly.

 

Just tighten down the onset screw enough to eliminate any stumble as the boost comes in. Thats the purpose of it. Don't just set it to 50psi because I told you to. Thats where it worked best for me, but I have a completely differnet combo than you. For one my base fuel pressure is ~42psi instead of the 25-30 you are measuring on your car.

 

I wanted to know, Is it possible to do a remote mount on a 86 Iroc-z with a carb 305? would i have issues with timing under boost?

Tim

 

which carb?

 

I have 3 different carbs I can use. 1 holly 650cfm, 1 holly 750cfm, and a quadrajet that is in excellent condition. I have an uncle who has extensive knowledge of quadrajets and said that he could tune it for almost any application.
Tim

 

blow through quadrajet would not be ideal. Even GM wouldnt try it when they carb turboed the first turbo regals.

 

I would stick with one of my hollys then. What sort of compression should I run if i plan to boost about 6-7psi?
Tim

 

9.0-9.5:1

I would just keep stock compressoin for such a mild boost.

 

I know that larger compression chambers will lower compression, but how much? I have a set of almost new 350 heads with 64cc chambers, my 305 has 58cc chambers. How much would that lower my compression?.... (any sceptics, keep in mind, I plan on using the 305 only to test how well the system really works on a carburated v-8)
Thanks,
Tim

 

 

If the 305ci is a test rig then use it as a test rig and don't put 350ci heads on it. 305ci heads were meant for 305ci engines. 350ci heads were meant for 350ci engines. It is that simple. Save the heads for a 350ci. If you really want to try something with the 305ci then re-cut the 305ci chambers for better flow and this will also reduce the compression ratio. That would be worth a try if you want to play around with the cyl. heads.
What is the actual compression of the "real" engine you intend to use? If it makes you feel any better, I am putting turbos on a stock 305ci TPI 9.5:1 compression engine and plan on running 6PSI on the street. It will be fine. Use good gas & less timing. I am also using a big charge air cooler. Hot air makes engines detonate easier. Detonation is bad for engines.

 

89JYTurbo, i am thinking about answering your call out to try this Remote mount build up on My Iroc. I have been looking at the STS kits quite a lot and if i cant buy one that bolts right now maybe i should try building one. Nothing a little welding and some time cant accomplish right. I understand how turbos work and all, but my main concern is picking one out of a junkyard that will provide sufficient boost to run my 355. Ive been building this "blower" motor for quite some time , but long story short, i have a 355 block with a full forged bottom end and a static compression of 7.5:1. Obvously i cant use this motor unless it has boost, so my main question for anyone listening, is what kind of turbo should i look for in a Junkyard. I work at Advance and one of the junkyards that we deliver to said they have 3 turbos off from dodge 2.2's and 2.5s that why would sell me for 20$ a peice and tehy work fine. Would one of these turbos be enough to give me like 5 pounds of boost to see if i like the set up before i drop 700 on a new turbo?

I'm running a stealth ram set up and am going to buy the Holley Standalone Fuel managment system for the stealth ram to convert the MAF to MAP on 20% discount

 

89JYTurbo, i am thinking about answering your call out to try this Remote mount build up on My Iroc. I have been looking at the STS kits quite a lot and if i cant buy one that bolts right now maybe i should try building one. Nothing a little welding and some time cant accomplish right. I understand how turbos work and all, but my main concern is picking one out of a junkyard that will provide sufficient boost to run my 355. Ive been building this "blower" motor for quite some time , but long story short, i have a 355 block with a full forged bottom end and a static compression of 7.5:1. Obvously i cant use this motor unless it has boost, so my main question for anyone listening, is what kind of turbo should i look for in a Junkyard. I work at Advance and one of the junkyards that we deliver to said they have 3 turbos off from dodge 2.2's and 2.5s that why would sell me for 20$ a peice and tehy work fine. Would one of these turbos be enough to give me like 5 pounds of boost to see if i like the set up before i drop 700 on a new turbo?

I'm running a stealth ram set up and am going to buy the Holley Standalone Fuel managment system for the stealth ram to convert the MAF to MAP on 20% discount

 

I'm going to say that one of those little turbos probably would not be enough for a 7.5CR 355ci engine. IMO you would probably need two of them. Somebody else here probably knows more about those particular turbos than I do, so hopefully they'll let you know if those would get the 5PSI your looking for.

 

Wow. Thats low compression. Provided the chambers are efficient and your tune is good, you should be able to run a ton of boost. You may need more than 5psi of boost to wake up that slug. Those turbos are way small for single use. Two of them should work out well for a mild boost, but they will probably be undersized for anything serious (off the top of my head I'm going to say they will be out of airflow at around 10psi of boost, but there are a ton of varibles).

 

CR drop will depend on what the CR is now (sorry, I’m not really picking on you, but you keep asking questions that do not have a real answer because you don’t give enough detail), but to give an idea, a 9.3:1 TPI engine (most fell in that range even though they were rated higher) will be about 8.7:1 with a set of 64cc heads with the same head gasket volume (ie, thickness and bore diameter). Of course, you gasket bore diameter will probably go up.

I’m not sure about the fuss about 305 vs 350 heads… they’re all small block heads and there have been all sorts of combinations over the years. I would strongly suggest against hogging 58cc chambers out anywhere near 64 cc’s… like most late, lightweight castings, there just isn’t the iron there to do it without damaging something.

If you were going NA I’d probably suggest notching the cylinders to make up for the larger valves, but with boost that shouldn’t be a problem.

5lbs boost on a 7.5:1 engine is still going to be pretty useless… assuming that the thing has heads and cam to match the SR, you probably won’t see anything useful with even twin small Chrysler turbos (a pair is probably good for 400-450hp, the SR, matching heads and cam should be pretty close to that), and either way, to wake up a 7.5:1 combination you’re really looking for more like 15psi boost.

For that matter, I’ll buy a rear mount for situations that you can’t do anything else and street use, but that is not really a compatible combination for a 7.5:1 purpose built engine. By the time that you get something that will flow enough air to really have some fun with that you’ll have a hell of a time getting it to spool back there and when you do it will not be a fun combination on the street.

 

I was going to say that too. I just forgot to tack that on in my last post.

 

Has anyone put a rear mount turbo on a v6 camaro?
Tim

 

I think its do able using the same setup that was used on the cavalier, but why bother when you have all that room?

and someone making hardware like this?

http://www.bbsdesigns.net/

Edgardo is a member here even.

 

On a V6... with all that room all you have to do is weld up some tubign to match up to what's there already... it would be less work then makign a rear mount setup.

 

I suppose your right. I know that third gen v6 camaros have alot of room, but the 4th gens dont have as much. I am just curious as to how much power that would make in comparrison to a traditional setup.

 

The power would be very similar if you compare street oriented turbo systems. You just don't consider RMT for a purpose built racecar, so the comparision is not needed. In general, you size the turbine section of the turbo smaller than ideal for RMT use to keep the response in line. Obviousely this is going to cause you to loose some top end HP, but you could still make a RMT 6 banger F-body run respectable 1/4 times.

 

Check out TRTTURBO.com for some of our cars and dyno sheets to see how much power the rear mounted turbo's are making.

 

Sorry to keep bringing back an old post.

I just got my Z24 dynoed this past week. Put 328HP and 352TQ to the front tires. I was pretty happy with those numbers. I can't wait to run my TT IROC on the same dyno with the new turbochargers (it put out 328WHP and 467WTQ on a dyno at the Wildwood NJ cruise three years ago, being strangled by 50 trim Volvo TC's, I have not dynoed it since).

Dyno Sheet:
http://www.khturbo.net/images/Z24ima...no%20Sheet.jpg

Video (6.5MB):
http://khturbo.net/rmtz24/Z24DynoMovie.wmv

 

Man, that is crazy.
That was with water injection right?

LSwhat?

BTW, what are the stock power specs on that 3400?

 

Thanks Steve. Yes, that was with water injection. I went lean above 5k on the first run without the alky spary. The alky pulled the AFR down 2 full points at the same area! After seeing the second run with the alky, the dyno operator said "yeah, all the runs from now will be with the alky on." The power also improved with the spray, adding about 20hp and 20lbft at the peaks. At one point, around 3-3.5K, the alky was worth an additional 30hp and 32lbft! Maybe with better fuel managment, the differences would be less, but I was still impressed (it seems funny that something so cheap and easy can make such a difference).

The 3400 are factory rated at 185HP, and 210TQ. I've seen several of them swapped into the J-body cars. One guy got 159WHP bone stock with the 3400 in a J (probably didn't have an excellent tune). Another had some bolt-ons, and he had (IIRC) 183WHP and 195WTQ. These NA 3400 swaps in the J-body usually net around a 14.5 1/4 mile at 95mph. Keep in mind we are only pushing about 3,000lbs with the driver, so you don't need quite as much HP as an F-body to go just as fast. FWIW, my Z24 weighed exactly 3000lbs with me in it the last I had it at the track, versus 3700 for the TT IROC.

 

Nice. It's good to see real dyno results from alky injection. I bet the difference would be much greater if you were running more boost (91-93 octane doesn't like 24 psi, hehe. Just ask my daily driver. )

You're getting roughly twice the whp from only 10 psi? That's crazy. I want to go into why, but don't feel like it right now, heh. You know though. This seems to be the rule, rather than the exception, which I find interesting.

Have you ever heard of E85? If you can get any in your area, try it out on the Cavy if your fuel system is up to it yet. I can tell you that you'll never need alky injection again. (BTW, E85 very much does like 24 psi. Ask me how I know. )

Either way, you've done proven this RMT setup time and time again. For what you get, who really cares if it spools 300rpm sooner and makes 12 more hp with an "FMT"?

 

I agree. Take my IROC for instance. Probably 200WHP or so box stock, add a PR of 1.4 (6psi of boost), and you end up with 328WHP?? Thats a lot more than the 40% you would expect from 6psi of boost (and I gaurantee my new turbos will produce more HP at the same boost level). I always wondered how this can be possible, and it sounds like you have seen it many times. What is your theory?

 

Yes, it seems to be the case with all the N/A gone turbo cars I see dyno numbers from. I'd think that maybe some of the cars would gain more power than manifold pressure, but most would not gain as much, or at least be equal. It seems that it's a pretty common trend for this to happen, and here's a few idea's I have as to why...

Part of it may be that the extra parts you add on or take away while doing the turbo setup make better power even without boost, like turbo headers may flow better than stock manifolds, or the new turbo exhaust may be better than stock exhaust, etc.

However, you have mostly stock parts on both these cars. Didn't you say that the Cavy has a stock or mostly stock exhaust until the turbo? The intake pipe may flow more than N/A, but that would only be a few hp. I know you're using stock manifolds on the IROC, and running it all through a muffler. So, none of this makes too much sense.

I think that the answer may lie more internally, with VE. Obviously you're increasing VE with boost, but maybe the reaction as a whole works better for combustion, like fuel atomization for example. Pressurized air probably makes more of an impact on the incoming fuel, mixing it better with the air. This also reduces the need for proper quench, which few stock engines seem to have (at least stock SBC's).

Another possibility is that the force from the higher intake air pressure helping the piston down and crank around may be greater than the force from the higher pressure resisting it on the way back up on the compression stroke, but this doesn't make much sense as it should be relatively equal. It may at least smooth out the transition some.

Yet another idea is that the turbo(s) changes the mass airflow curve in just the right places to work better with the otherwise N/A parts, increasing VE.

On last thing I can think of is the cylinder pressure 'curve' (think line graph, like a dyno chart) during combustion. N/A engines should be real peaky while the boosted engine should have a broader curve (like the dyno chart with more 'area under the curve'). This would increase power and torque beyond just the extra atmospheres.

Other things to consider are the whp numbers. You don't lose a solid percentage through the drivetrain like some people think, but the loss percentage becomes less as you make more power. (Otherwise a 1500hp turbo V8 would be losing 300hp at 20% loss through the drivetrain, and that doesn't happen. The heat created from that would be insane)

For example, say you lose 14% at N/A power levels (185bhp vs 159whp), but only lose 10% at the boosted power levels (365bhp vs 328whp). You then gained 97% at the crank, but 106% at the wheels.

These things and other possibilities may not make much difference alone, but added up they might give you a 106% increase in power to the ground with only a 68% increase in manifold pressure (since you live around sea level, right?).

Also, your N/A 3400 Cavy may have made more than the other guys too, but I doubt it was all that much more, and your guesstimate of 200whp N/A in the IROC sounds about right. That's a 64% whp increase from 41% more manifold pressure.

If I'm wrong on any of this by people who know, please correct me and add your explaination.

 

BTW, I hope this happens with my IROC too because the intercooled 15 psi I plan on being able to run with E85 should make for one heluva 500hp 650 lb/ft TPI beast.

It may not happen due to deadlines and whatnot (doh), but I 'should' be able to get my IROC to a dyno N/A once I get back and fix the T56 bellhousing and install a SPEC stg III, then I will dyno it boosted once I get it tuned, hopefully on the same dyno.
I'll have a whole month off just to work on the car so it -shouldn't- be a problem. *crosses fingers*

 

SORRY?????????Keep it coming!!!The most informative post on doing MORE with less!!!

 

Sorry to bring up a hijack again, but it is your thread afterall, and you don't seem to mind.

Talking to my friend Will, the physics major/gearhead (heh), about the pressure vs power situation, he had this to say, and it makes total sense:

"The factors that conspire to make a relatively low output N/A emissions engine also conspire to make one that's very friendly for boost. Boosted operation isn't just N/A operation only more so... it's dramatically different because of the differential pressures at the intake and exhaust. The low overlap does not make for good N/A performance because it does not provide for scavenging, but it does a good job isolating intake from exhaust and making good use of boost pressure in a FI engine.
For instance, in N/A form there are roughly 15 psi of pressure pushing air into the cylinder. There are no extra helpers from scavenging, only from intake tuning in the case of the TPI. As air flows into the cylinder the pressure difference across the port drops and flow drops off as well. Near the end of the intake stroke, with the piston starting back up the bore, the pressure difference is so small you can actually get some reversion back into the intake primary. The resonant tuning helps with this, but not entirely.

In a boosted engine, you have 30 psi of air pushing through the port, but port flow is proportional to the square root of pressure difference, not directly proportional, so the port flow doesn't go up as fast as manifold pressure. BUT, because the port isn't flowing as fast relative to pressure, the pressure difference across it persists longer in the intake stroke and makes fuller use of valve open time.
You can accentuate this by using a cam with the same overlap (measured in degree-inches, not simply degrees) as the factory cam, but more lift and more aggressive ramps."

Well said, I might add.

 

Ok, I'm looking into a remote turbo for my car and I'm wondering if for cooling I just rigged up a closed oiling system that had the oil go through a cooler, through the turbo and then have a pump in there somewhere. Would that work, to be completely isolated form the engine?

 

Yes, you can make that idea work, but I can't give you any exact details. I was going to try a 'divorced' oiling system for this project, but abandoned it for a simpler engine lube system.

With a divorced system, you would need a reservoir for the oil to drain into, as well as a pump that can supply a constant 40+psi of oil pressure at high oil temps. Depending on the turbo lube system's capacity and the cooler you choose, the actual temp will vary. So if you are doing R&D on your home brew turbo lube system, you will also need oil temp and pressure gauges to keep tabs on the vitals. The only advantage I see to a divorced system is that you don't need to run any oil lines under the car. However, these oil lines are nearly impossible to damage if you use common sense in your routing and use good hose- I actually used metal 1/4" brake tubing for my oil feed and 3/8 metal piping for the drain. I used hydraulic hose for the areas that needed some flexabilty.

 

Ok, that makes sense. I'm seriously considering doing this. I just need to figure out the piping. I'm thinking of getting a catback for that and running it paralell to the exhaust, but I'll need to get the thing in the air and have a look.

 

89JY...I picked up a cheapo boost controller and was wondering with a rear mount setup is it best to run the boost controller between the throttlebody and the wastegate????it would be a long vacuum line?thx,mike

 

I made my own boost controller (2 stage) and have the solenoid mounted in the trunk. A long vacuum hose from the TB back the the WG may give you trouble controlling boost.

 

I just picked upa set of turbo injectors and a ECU from a 86 300zx turbo car....cant wait to see the differance!!

 

just a not that I read this entire post and have found it to be VERY enlightnening. Been trying to frind info o RMT for my Blazer and was thinking a t3/t4 hybrid would be right. THX for all the info!

 

I finally got around to installing my turbo injectors/ECU and its amazing the differance in how the car pulls!!!Before with the n/a injectors and the BEGI it was pulling nice, but with the new parts its a new ANIMAL.i'LL PROBABLY KEEP THE BEGI installed and up the pressure inthe future when i up the boost...still alot of potential left in this car for very little investment!!!

 

Cool.

 

isnt there crazy lag with these things? why not mount in the engin bay?

 

Didn't you read the thread? Why not read the thread?

 

agreed, why ask something so covered well in the thread?

 

i dunno it was 6 pages and i was at work so i couldnt read the whole thing, just askin a quesion dont crucify me lol... dont worry ill read the whole thread......... thanks guys

 

all you guys are reallly good at this turbo stuff and lets just say im not well i have a 90 iroc-z convertible and want to do the rear mounted turbo set. the iroc has a 305 motor that im going to change to a l98. is there any turbo that i can use on a 305 but still work good whit a 350 and if there is not what caind of turbo is good for a 305 and what turbo is good for a 350 everything els i think i got it i have read all the post and they help. and one more question the turbo use oil from the oil pan so you tap in to the oil pan and connect it to the turbo thats it rigth then to punp the oil back we use a oil pump. pleas i need help thank im clueless