how about a little teaser.... this is one of the more wild combo's 19.5 to 1 comp, stock valve size, mild porting, ball bearing turbo 88mm compressor, rich burn rate, 20psi boost, 1355 exhaust temp, 3229 psi cylinder pressure, 848 torq@2200rpm 442@3200rpm. computer says theres more in there if you can keep it together at more heat and pressure levels. I am having problems importing my info to a graph that will be good on this forum.

 

88mm? A bit small isnt it?

 

Well the garrett GTP 38 can be fitted to a psd turbo mount and I want to try and use psd manifolds and up pipes on my engine. It also had a turbo performance map for me to use on the dyno program. The info is only as good as the data entered so it made sense to me to use a turbo I could get a map for. Looks like I may need to graph all my data and run it through my scaner then import them like a pic so I can make ajustments to the size. Im working 6 days a week right now so It might take some time to get it up here..

 

How on earth you're gonna spool an 88mm turbo is what I'm wondering. I've NEVER seen anything that big used as a single (heck possibly even as a secondary in a twin setup) on a street driven diesel, much less on an old IDI International.

Or am I just missing something here? My knowledge of these IDI's is fairly limited.

 

well lets back up a little. I have been running alot of different cam grinds on the dyno program. i have used NA and turbo applications with stock heads and mild ported heads. I have used several different turbo maps for comparison. I have tried to stay with products that will bolt on or can be modified to fit. The 88 is just one turbo that I ran in a max performance drag or puller type combo with ROLLING COAL fuel setting and 20 psi boost. I don't now if it will work in the real world but...It was kind of fun to run one on the dyno just to what it would do. I know that the real performance of this engine will come from were the rubber hits the road kind of guys on this type of site. using trial and error "hopefully less error" with their builds. Here is one that is nice. Stock heads Stock turbo waste gate set to 12psi "TYPE 4" torq cam fuel turned up. 574 torq@3000 336 hp@3200 divide by 1.3 for drive train 441 torq 258 hp this is a verry possible combo exhaust temp 1250 cylinder pressure 3519 psi got more with more boost but temps go up fast from here with stock comp of 21.5... got good numbers when I drop to 19,6 comp then you can lean on it with more boost. just a little worried about cold start problems. might be like starting a worn out idi on 6 plugs....

 

Ok if this works I will follow this with more data. First I will say this info was gathered from many places on the web, to many to quote all of them, so I will put that info in when its most important. this data is only for comparison of cam profiles on the IDI diesel engine. I have said that the cam is what is holding the engine back with its 38* of overlap and 240* duration 0n intake and 250* on exhaust. All the performance cams I looked into had less duration and more lobe separation. All the cam profiles I ran on the analizer were on the lobe chart from Oregon cam grinding. Accept one the cam from TYPE4, None of them made as much low end torq as the type 4 grind in a stock engine.... when you start turning the boost the engine really comes to life.. the problem is the stock compresion ratio in combination with added boost put the engine pressure and exhaust temp into the danger zone verry fast. This first graph is a comparison between stock 94 turbo engine with 6 psi and a stock engine with a type 4 cam and 10 psi boost to simulate basic mods anyone could do.... heres the kicker..same fuel ratio in both runs. aprox 23 to 1 as per the dyno. we will talk more about that later. cool it worked just click on the graph to make it bigger. more to come.

 

Basic engine calculations can give a baseline to use for getting the performance into the rpm range you are looking for. the machanical efficiency of the engine plays a big roll in the production of hp and torq. the 7.3 engine has alot of weight spinning around inside trying to get out. It takes alot of money to solve this problem. So I think trying to get this engine to rev up past 4000 would be asking alot of the parts we have available to us. with this info it seems the making of power in the 1000 to 3000 range would be most important to most applications. any extra rpms would be a plus but it comes with a price tag. The stock 7.3 has aprox only 86% volumetric efficient and a stock turbo engine is 97% with 6 psi boost. The engine jumps to 131% volumetric efficient at 9 psi with a type 4 cam. "all measured at max torq". The cylinder pressure is what makes all the power reach the crankshaft so it is almost a given that more pressure is more power. Right up to when the parts break. 3006 psi cylinder pressure = 269 hp 545 torq +or- a little. 3570psi = 335 hp 652 torq, 1200* exhaust temp. this was 21.5 to 1 comp. The 7.3 engine uses 70.3 hp at 2700 rpm and 148.7 at 4000 rpm just to run. this was with stock piston skirt friction. as you can see there is alot going on inside this bad boy. the program has 4 fuel settings, truck lean low smoke, auto rich low smoke, race rich some smoke, race rich performance pump. 23 to1 20 to 1 18 to 1 and 15 to 1 air fuel mix. The numbers go up with more fuel as expected. Remember all my numbers are crank shaft hp and torq, its getting late the wife just gave me that look, time to go. more graphs to follow.

 

thats impressive, i knew idi's had potential!!

 

Next thing to talk about ,Dynamic compression ratio, this is what makes the engine run. It was changed when we changed the cam valve timing. There are several ways to calculate this and I get a differant ratio based on weather or not I tell the calculator about the turbo. the theoretic compression ratio is verry close on both calculators so I think its accurate. the stock engine with 6 psi boost and advertised compression of 21.5 to 1. has a effective stoke of 3.76" a dynamic compression 19.34 to 1, boost compression ratio 27.23 to 1 . with the type 4 cam and 6 psi we get a effective stroke of 4.3",dynamic ratio of 21.15 to 1,and a boost ratio of 29.78 to 1 this makes for more power in a stock engine. When you look at making more power in this engine you need to look at the engine pressure you need to make the power you want and the most effective way to get there. The psd engine has dropped the advertised compression and added more boost. The idi engine was designed as a na engine and had a turbo installed from market pressure from the "other" truck guys. When I put more fuel and boost in the engine it makes big numbers but we know this engines head gaskets will only take so much... So when I lower the static compression ratio to 19.6 to 1 and raise boost to 15 it has 4.13", effective stroke, dynamic comp 19.28 to 1 and boost comp 38.95 . the engine picks up more power from the added air and takes fuel better though the power range without going staight to high temps and cylinder pressure. When I tryed to graph this info the numbers pile up on each other and look like crap. My next graph will be the lower compression results, now don't get to freeked out about the numbers the dyno seems to be verry generous, the trends in the data are what I'm realy after.

 

Alright please forgive me on this next graph the numbers would stack up when I printed it so I printed it without data and put them in myself. ok now the temps are from the exhaust valve so they could be a bit high compared to a pyro in the manifold by number 8 cylinder that would be almost 8 to 9 inches from the valve seat. oh the type 4 run was on turned up fuel and 15lbs boost, You can see on the graph were the waste gate opens then the torq drops off. when I turned up the boost the torq line keeps climbing at the same rate until it opens again. we all know boost makes power so when the waste gate opens the rpm keeps climbing but the cfm of air drops off compared to what was going into the cylinder at the point the turbo stopped increasing boost. the trick will be getting the waste gate to open in the range we are looking for and stay in the safe temp and pressure zone. my goal here is to get good performance without making the engine into a grenade.