The "4.9 liter turbocharger, stage 1" thread.

[illumina]

http://www.amghummer.com/Diesel/GM99...ifications.htm

Here you go. This is about the best I can find right now. It is for a '99 model engine, but all other 6.5 liter turbodiesels should be similar in output. Hopefully you can work with this.

[N0DIH]

8 psi is what the http://www.thedieselpage.com/reviews/rogerstory.htm indicates is around stock.

Redline is likely around 3400 rpm as this picture looks like. http://www.thedieselpage.com/reviews/gauges2005.htm

Originally Posted by illumina

Sorry, I don't. Maybe Tom will have something for us when he posts again. I will tell you that I heard somewhere that it was 8 psi or more, but that would be very unconfirmed...

Redline I simply don't know either...Maybe I can dig up a dashboard panel picture from a Suburban or something...Lemme go and see...

[Formula94lt1]

Do not base the sizing of a diesel turbo and how it was used and performed on a diesel to a gas motor with the same turbo... Diesels have more exhaust energy than gas engines. It would be a DAMN good idea to find out the compressor maps like Call me crazy is trying to do rather than judge the outcome based on engine displacement and rpms of a different engine that had the same turbo The VE of the 2 engines are probably different at different rpms etc. so it makes it even more vague an assumpstion to go by... I think it would be hard to hurt a motor with 9.5:1 static compression with 6psi assuming it is properly tuned, if not then all bets are off, especially with an intercooler....

[N0DIH]

Considering diesels run roughly the same amount of air per revolution (350 CID for a 5.7L, etc), no vacuum in the intake, where a gas engine has a vacuum, so very little, controlled air. You are very correct.

My fear is the cyl pressure will be too high, and you will result in piston breakage and blown head gaskets. I would be very cautious with the rpm at which the boost arrives, hence why I would recommend a slightly larger cam to help bleed off some cyl pressure and a larger turbo so that boost is lagged or delayed until 3500 to 4000 for peak boost to occcur.

Even the famed LT1 can't take more than 6 psi turbo boost, I doubt that Cadillac has better pistons in the 4.9L than the LT1 has.

My advice is boost with caution. Take advice from the diesel 5.7 guys. GOOD gaksets, strong as you can get head bolts, and if you can stud the mains, do it. Do not underestimate the forces a boosted engine can do.

Consider my 301 Turbo, 290 rwhp (rated 210hp, calculated 290 rear wheel hp, based on 14.21@97.3 mph 1/4mile, 4030lbs, and 3.08 gears) and if you ever saw a 301 heads, crank, cam, and turbo, you would be amazed at what it did. That was with a 301 CID engine, 7.5 psi boost (low for a 301, stock is 10 psi), a beefy turbo block, HD pistons with the offset turbo dish, and a static compression of 7.5:1. So starting off with 9.5:1, and no timing mangement for pinging under boost, is the starting of a recipe for distaster.

[illumina]

Originally Posted by N0DIH

So starting off with 9.5:1, and no timing mangement for pinging under boost, is the starting of a recipe for distaster.

Actually, that is the first thing I considered when I began researching this project. That's why I bought the MSD boost-timing controll system...I just need a new MSD ignition for it to work as I purchased that item to work with it...

[N0DIH]

Does it allow for a knock sensor input? In my really disasterous experience, pinging is piston lightening deadly. Being I don't have a EST module car anymore, I can't play and experiement with adapting the ESC module to the 4.9L V8. I would love to. (anyone got a 90-95 4.9L car to donate/loan for a while while I test?) I need to connect an oscilloscope to the EST line to the module and see what is on it, and then determine how ot interfere with it to reduce timing when pinging is heard. Also need to find a knock sensor that is tuned for a 4.9L. That may be more difficult.

[stickpony]

if you visit the pennock's fiero forum, there has been alot done to the 4.9L caddy engines for performance, including turbo charging...there is alot of info on the type of engien mods you are doing to the 4.9L.. unfortunately, because the 4.9L cadd engines dont use a knock sensor, youll have to use an entirley different computer if you plan to use more than 6 psi boost... visit www.fiero.nl

post on the group about what you wnat to do.. there several hotrodding build up threads for the 4.9L engines and also some about turboing it as well.. take care

[stickpony]

heres a thread that tells how to build up the 4.9L , including a cam change to the delta cams .496 lift cam, head work where the intake valves were increased in size, and an allante intake manifold was used http://www.fiero.nl/forum/Forum2/HTML/061613.html

[stickpony]

heres info on a 4.9L turbo install..

http://www.fiero.nl/forum/Forum2/HTML/064940.html

[stickpony]

and this one too:

http://www.fiero.nl/forum/Archives/A...-2-045542.html

[N0DIH]

Here is some good reading too.

http://encyclopedia.localcolorart.co.../Turbocharger/

[illumina]

Originally Posted by stickpony

heres a thread that tells how to build up the 4.9L , including a cam change to the delta cams .496 lift cam, head work where the intake valves were increased in size, and an allante intake manifold was used http://www.fiero.nl/forum/Forum2/HTML/061613.html

Thanks for the great link!

However, when I do my 4.9 rebuild (after stage 1 install is complete), I will not be looking to increase the compression ratio with the Northstar pistons. I will likely do some combustion chamber work to lower the compression ratio to run a little more boost. I have an idea for about an 8.5:1 comprssion ratio when stage 2 is finished running closer to 10 psi of boost.

As for the components I will likely use for stage 2:

Ported and polished heads. Aforemetioned work to lower CP ratio.

Roller rocker arms with Allante steel supports. 1.6:1 rocker ratio will be used, and stock is 1.6:1 ratio.

Camshaft...I might get away with just higher lift while leaving duration and such alone so I don't have to worry about ECM changes...Am I able to do that with a regrind for just lift? Put it like this, I can change to a 1.7:1 rocker ratio to increase lift without doing any ECM changes. The ECM work is needed only for profile changes...I think.

New internals are a must! Chrome molly rings are good and I installed a set in my '87 Seville 4.5 liter engine.

I like that Allante intake setup. I would be willing to change things around to run with an Allante EPROM and such. Wiring is the key here...I also know a place that will sell me an Allate intake (upper and lower), valve covers, rocker support bar (steel), and fuel rail for $250.00.

Then run 10 pounds of boost...Yeah, that sounds about right!

Originally Posted by N0DIH

Does it allow for a knock sensor input? In my really disasterous experience, pinging is piston lightening deadly. Being I don't have a EST module car anymore, I can't play and experiement with adapting the ESC module to the 4.9L V8. I would love to. (anyone got a 90-95 4.9L car to donate/loan for a while while I test?) I need to connect an oscilloscope to the EST line to the module and see what is on it, and then determine how ot interfere with it to reduce timing when pinging is heard. Also need to find a knock sensor that is tuned for a 4.9L. That may be more difficult.

Tom, unfortunately it does not. There is however a knock sensor kit that can be plugged into an engine drain plug or what have you from Jegs. They run at about $150.00 or so. They don't do an automatic retard that I'm aware of, but it does alert you of detonation and you can thereofre use the MSD to retard the timing scale for boost. From what I've seen, that would be the single best investment that I could get away with.

[N0DIH]

For stage II I would like to see more like 8-8.2 compression. More boost is worth far more than higher compression will ever get you.

Something to consider is ditching the Cadillac ECM. But you lose some cool FDC functionality. That is a downside. But if you go something like a LT1 (pre 96) ECM, or a L98 TPI computer (TPI 350 and TPI 305 ECM's like HEI's, where LT1's like Optisparks, unless you can adapt a 360 degree crank position sensor to the HEI or to the front of the engine), you gain full aftermarket support. And they have knock sensor inputs too. You need the fast speed of the automatic knock retard, believe me, working with mine running the way it did, with 7.5:1 compression and 7.5 psi boost with knock retard, with me pushing the timing as high as 93 octane would allow, pinging still would get you when you didn't want it to. Like at 120 mph when you try to cruise and vacuum advance kicked in!!! RATTLE CITY. I had to be at WOT or no throttle to maintain 120. I know why GM was so bloody conservative on that engine. The ECM in the Cad doesn't know anything different. Sure, no vacuum adv, but it will think there is no reason not to up the timing at light throttle at 100+ mph.

And the knock sensor is specific to the frequency of the cyls. The wrong sensor would be someone deaf to the engine. So you may need to get an array of sensors to try and connect an oscilloscope to so you can measure pinging. One will work better than others. I wonder if you can use a microphone to analyze the engine sounds in pinging.

A good friend of mine is a head guru would be glad to give you some tips to lower compression safely. Grinding the wrong thing on the heads can make for poor flame travel. Take some good pictures of the chambers on a 4.5/4.9 and send them to me, I will see him soon. Or even Blaze might see him sooner.

Olds guru's like to use Ford 351 Roller Rockers (302 too?) for the Olds V8's. Cad 4.x engines LOOK to be nearly identical to the Olds in rockers. You can likely easily adapt them to the 4.x. 15hp boost on any 4.x. Cost, maybe $150. I think you can get 1.7's. Cam regrind will keep duration very very close. The smaller base circle of the came needs to be examined in the block. If the lifter goes too low you can run into issues with lifter bosses breaking due to excessive forces. I don't know the 4.x lifter valley that well. Turbos love lift, they are not so caring of a lot of duration. Keep it low, a 200/200 cam in a GN is a "big" cam. So keep it down, more like stock should be fine. The turbo will greatly broaden the powerband where you don't need it. If you are racing, then it matters. This is street power. The smaller cams will make the boost more restrictive at higher rpms, as with the valves open less of the time there is more backup, where a larger cam allows for more time to pack the cyls with more. And more sudden open plenum area such as the cyl, drops charge temp a little bit more.

Turbo's don't need tuned intakes, they can make the engine peaky. But do give it as much flow as you can, it will use it. The more plenum volume the less need for intercooling. How many semi's do you see with intercoolers? None. How many with aftercoolers? All. Design for aftercooling. It is basically adding a large plenum area after the turbo exit that allows some room for the turbo boosted air to expand into some, causing the air charge temp that was heated by the adiabatic heating/cooling of the turbo to cool down some. This will help overall a lot. Almost like coming out of the turbo into an intake like the GN Regals only with a larger plenum top area than the GN had, but keeping the same size runners. You want velocity way up. I would honestly bet that a creative nut could adapt a Buick 3.8 or 3800 intake (need 2 to merge) together to make a V8 intake that would support a sweet intake for the 4.5L/4.9L.

I'm still sticking to no intercooler with 10 psi and lower. There isn't as much heating, so the added intake track for the intercooler increases lag time, and there isn't as much need to cool the charge off. Example, if the boost increases the charge temp to 150 degrees F, and it is 75 degrees out, you can only hope if 100% efficiency, to drop it to 75F. We know we won't get that, so it will maybe only cool it down to 100-125 degrees. Not much savings here for the large expense and difficulty plumbing it. Higher boost levels? Yes, defineatly worth it. When you are heating the air up to 200-250 degrees, you have to have it, and it is very worth it.

Nitrous is an awesome intercooler.... The super cool gas temp makes intakes nearly frozen at speed. And then the additional power is fantastic.

[illumina]

Tom, the reason I was thinking about the Allante intake is the exact reason you've stated: the plenum will help cool the charge air temps...Am I right?

Also, here is a picture of the combustion chamber from an HT-4100 cylinder head. The 4.5 and 4.9 liter heads are exactly alike in the combustion chambers...

See what can be done here. There seems to be enough material to lower the compression ratios to your idea of 8.2:1 or so.

Let me ask you this as well: you stated that the lower compression ratio would'nt take too much power away. What are the exact losses you would expect if it was lowered to 8.2:1? If we are dealing with an engine with a higher lift cam, roller rockers, Allante intake, and head work (the whole 9 yards on the heads), you're saying that the compression loss would be minimal? Please let me know...

Here is the picture of the head combustion chamber:

[N0DIH]

I will have to consult a friend of mine for more info, as he is a cyl head guru.

But what I do know:
1. This is a high swirl "heart shaped" chamber. There is mixed theories on whether or not you should destroy the swirl properties under high flow applications.
2. Do not mess with the quench area, the flat part that is opposite the sparkplug, it will invite a hiding place for fuel to hide and not have access to the flame front, which will cause HC emissions to skyrocket. As well as fuel not exposed to the flame is not making you HP.
3. I think initially I would widen the area around the valves, unshroud them, especially around the intakes. You should be able to gain some good Cc's there. As well as enhancing airflow around the intake valve.
4. CC the heads first, and then shoot for 6 cc to reduce 1 point of compression. If I remember my math right.
5. Avoid shaving heads, unless you have to, as it invites higher compression.
6. The square block around the spark plug is unqiue to the chamber performance, but I don't remember exactly what, I'll let you know when I dig it up.
7. Avoid excessive grinding of the valve seats. This causes the valve to recess sllightly in the chamber (which does lower compression slightly) but creates a delay time for the air/fiuel mixture to start flowing. There is additional shrouding created.
8. Do not stack head gaskets to reduce compression. this is a terrible invitation for blown gaskets, especially with blown apps.
9. I have been planning on building a low buck flow bench. Let me know when you are ready to start grinding and I will let you know what I have in the works.

the general rule of thumb is 1 compression point is as much as 4% hp increase/decrease. with 1 psi boost you might gain more like 5-10% increase. Consider for every 14.7 psi is double the CID (2 atmospheres), so your 4.9L is now a 9.8L. You'll need some extra fuel....